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Math 7 · Mathematics
Numbers · Rational numbers

Equivalent Fractions and Simplest Form

Before you start, make sure you know: Greatest common factor (Math 6)
Before you start, make sure you know: Concept (Math 6)

Maya has beaten $42$ of the $60$ levels in her favorite video game. Her cousin Jayden plays a different game with $90$ levels and says he has beaten the same fraction of it. How many levels has Jayden beaten? To answer, you need equivalent fractions: different-looking fractions that name the same amount.

Same amount, different names

A fraction $\frac{a}{b}$ tells you how many equal parts are shaded ($a$) out of how many equal parts there are in all ($b$). The parts must be the same size.

Cut a bar into 2, 4, or 8 equal parts and shade half of it. The shaded part is the same size every time. Only the number of pieces changes.

Three equal bars cut into halves, fourths and eighths, each shaded exactly half, showing that 1/2, 2/4 and 4/8 are the same amount. 1/2 2/4 4/8

Try the widget: change the numerator and denominator and watch the pieces.

Here is the number-line view. Both $\frac{2}{3}$ and $\frac{4}{6}$ land on the same spot between $0$ and $1$.

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In a chocolate bar like the one in the image, we have consumed the pieces that are colored orange. a) Write the fraction that the consumed pieces represent with respect…

In a chocolate bar like the one in the image, we have consumed the pieces that are colored orange.

  1. a) Write the fraction that the consumed pieces represent with respect to the whole bar.
  2. b) Simplify the previous fraction until you reach its irreducible fraction.
Solve
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Look at the following rectangles of equal size. The first one is divided into $4$ equal parts and the second one into $8$ equal parts. a) Write down the shaded fraction…

Look at the following rectangles of equal size. The first one is divided into $4$ equal parts and the second one into $8$ equal parts.

Figure A Figure B =
  1. a) Write down the shaded fraction of Figure A.
  2. b) Write down the shaded fraction of Figure B.
  3. c) Are they equivalent? Justify your answer by observing the drawing and performing the calculation.
Solve
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Draw a number line in your notebook and represent the following fractions on it. Demonstrate graphically that they are equivalent by observing that they are all located…

Draw a number line in your notebook and represent the following fractions on it. Demonstrate graphically that they are equivalent by observing that they are all located at the same point on the line:

$$\dfrac{1}{2}, \dfrac{2}{4}, \dfrac{4}{8}$$ 0 1 1/2 2/4 4/8
Solve

Making equivalent fractions

How do you get from $\frac{2}{3}$ to $\frac{6}{9}$ without drawing? Each third was cut into $3$ smaller pieces, so the numerator and the denominator both got multiplied by $3$.

Two bars of the same length: one cut into thirds with two shaded, one cut into ninths with six shaded, linked by a times 3 label. 2/3 6/9 (×3)

Every fraction equivalent to $\frac{4}{7}$ has the form $\frac{4k}{7k}$, where $k$ is the number you multiplied by.

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A group of friends is comparing the success of their social media posts. Ashley says that $2$ out of every $5$ followers have "liked" her latest photo. a) Write Ashley's…

A group of friends is comparing the success of their social media posts. Ashley says that $2$ out of every $5$ followers have "liked" her latest photo.

  1. a) Write Ashley's fraction of "likes".
  2. b) Obtain an equivalent fraction by expansion by multiplying both terms by $3$.
  3. c) Obtain another equivalent fraction if Ashley had a total of $50$ followers.
Solve
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To prepare a fruit smoothie, the recipe states that we must use $\frac{3}{4}$ of a gallon of milk. If we want to prepare a larger quantity keeping the proportion and the…

To prepare a fruit smoothie, the recipe states that we must use $\frac{3}{4}$ of a gallon of milk. If we want to prepare a larger quantity keeping the proportion and the new measuring jug marks eighths of a gallon ($8$ parts):

Find the value of $x$ so that the fractions are equivalent:

$$\frac{3}{4} = \frac{x}{8}$$
Solve
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Given the fraction $\frac{A}{B}$, we know that it is equivalent to $\frac{4}{7}$. If we add $12$ units to the numerator, for the new fraction to be equivalent to the…

Given the fraction $\frac{A}{B}$, we know that it is equivalent to $\frac{4}{7}$. If we add $12$ units to the numerator, for the new fraction to be equivalent to the original one, the denominator must increase by $21$ units.

Prove whether this statement is true for any initial value of $A$ and $B$ that maintains the proportion $\frac{4}{7}$. Next, find a fraction equivalent to $\frac{4}{7}$ such that the product of its terms ($A \cdot B$) is $700$.

Solve

Simplest form

You can also go the other way. A fraction is in simplest form (lowest terms) when the numerator and denominator share no common factor other than $1$, that is, when their GCF is $1$. Some problems call this an irreducible fraction.

The fraction 84 over 140 simplified to 3 over 5 by dividing numerator and denominator by 28. 84 140 3 5 ÷ 28 ÷ 28
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In the school library, the librarian tells us that $\frac{12}{30}$ of the books are adventure books. Help him simplify this fraction to put it on a poster: a) Divide the…

In the school library, the librarian tells us that $\frac{12}{30}$ of the books are adventure books. Help him simplify this fraction to put it on a poster:

  1. a) Divide the numerator and the denominator by $2$.
  2. b) Divide the previous result by $3$.
  3. c) Is the fraction obtained in part b an irreducible fraction? Why?
Solve
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Simplify the following fractions until you obtain their irreducible fraction. To do this, use the method of dividing the numerator and denominator by their greatest…

Simplify the following fractions until you obtain their irreducible fraction. To do this, use the method of dividing the numerator and denominator by their greatest common factor (GCF):

  1. a) $\dfrac{126}{180}$
  1. b) $\dfrac{210}{315}$
  1. c) $\dfrac{154}{198}$
Solve
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Find a fraction equivalent to $\frac{126}{198}$ that meets the following conditions simultaneously: 1. Its denominator is a number between $50$ and $100$. 2. The sum of…

Find a fraction equivalent to $\frac{126}{198}$ that meets the following conditions simultaneously:

  1. Its denominator is a number between $50$ and $100$.

  2. The sum of the digits of the numerator and the sum of the digits of the denominator are each, separately, a multiple of $9$.

  3. It is a proper fraction.

Explain step by step the process of simplification and expansion you have followed to find it.

Solve

Testing with cross-multiplication

Sofia made $14$ of her $20$ free throws. Mateo made $21$ of his $30$. Did they shoot equally well? Comparing $\frac{14}{20}$ and $\frac{21}{30}$ is quick with cross-multiplication.

The fractions 14 over 20 and 21 over 30 with diagonal lines linking each numerator to the opposite denominator; both cross products equal 420. 14 20 = 21 30 14 × 30 = 420 20 × 21 = 420

To test a whole list against one target, such as "which of these equal $\frac{2}{3}$?", cross-multiply each fraction with the target, or simplify each one.

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In a video game, you have collected $45$ coins out of a total of $60$ that were in the level. On the other hand, your brother has collected $15$ out of a total of $20$…

In a video game, you have collected $45$ coins out of a total of $60$ that were in the level. On the other hand, your brother has collected $15$ out of a total of $20$ in his game.

Use the cross-multiplication rule to check if the two fractions of collected coins are equivalent.

Solve
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Identify, from the following list, which of the fractions are equivalent to $\frac{2}{3}$: $$\frac{4}{6}, \quad \frac{5}{9}, \quad \frac{10}{15}, \quad \frac{6}{8},…

Identify, from the following list, which of the fractions are equivalent to $\frac{2}{3}$:

$$\frac{4}{6}, \quad \frac{5}{9}, \quad \frac{10}{15}, \quad \frac{6}{8}, \quad \frac{20}{30}$$
Solve
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An influencer* analyzes the impact of their videos. In the first one, they obtained $36$ "likes" for every $80$ views. In the second one, they obtained $45$ "likes" for…

An influencer analyzes the impact of their videos. In the first one, they obtained $36$ "likes" for every $80$ views. In the second one, they obtained $45$ "likes" for every $100$ views. Use the cross-multiplication rule to determine if the success proportion is equivalent in both videos.

Solve

Finding a missing number

Now back to Maya and Jayden. Maya's fraction is $\frac{42}{60}$. Jayden has beaten $x$ of $90$ levels. The equal fractions give $\frac{42}{60} = \frac{x}{90}$.

Steps to solve 42 over 60 equals x over 90: cross-multiply to get 42 times 90 equals 60 times x, then divide to find x equals 63. 42/60 = x/90 42 × 90 = 60 × x x = 63
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Copy into your notebook and complete the missing term in each case so that the pairs of fractions are equivalent: a) $\frac{1}{3} = \frac{\Box}{12}$ b)…

Copy into your notebook and complete the missing term in each case so that the pairs of fractions are equivalent:

  1. a) $\frac{1}{3} = \frac{\Box}{12}$
  1. b) $\frac{10}{15} = \frac{2}{\Box}$
  1. c) $\frac{\Box}{7} = \frac{20}{28}$
Solve
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In an esports competition, a player has completed $42$ of the $60$ levels of a video game. Another player has completed the same proportion of levels, but the game they…

In an esports competition, a player has completed $42$ of the $60$ levels of a video game. Another player has completed the same proportion of levels, but the game they are playing has a total of $90$ levels. How many levels has the second player passed? Solve it by finding the unknown term $x$ in the equality of equivalent fractions.

Solve
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Find the value of the unknown $n$ in each of the following equalities so that the fractions are equivalent: a) $\dfrac{n}{15} = \dfrac{12}{45}$ b)…

Find the value of the unknown $n$ in each of the following equalities so that the fractions are equivalent:

  1. a) $\dfrac{n}{15} = \dfrac{12}{45}$
  1. b) $\dfrac{7}{n} = \dfrac{28}{36}$
  1. c) $\dfrac{10}{18} = \dfrac{25}{n}$
Solve

One scale factor, many fractions

Sometimes a problem does not hand you one term. It gives you a condition: "the terms add to $56$" or "the area is $192$". Use the scale factor $k$ to turn the condition into an equation.

A small rectangle with sides 4 and 3 and a larger similar rectangle with sides 4k and 3k, showing that every equivalent ratio is the original times k. 4 3 4k 3k
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In a robotics competition, two robots must cover the same distance. The first robot has completed $\frac{42}{105}$ of the route, while the second robot has covered a…

In a robotics competition, two robots must cover the same distance. The first robot has completed $\frac{42}{105}$ of the route, while the second robot has covered a fraction equivalent to the previous one, but its numerator and denominator are natural numbers whose sum is exactly $112$.

What fraction of the route has the second robot covered? Justify whether both robots are at the same point on the track and calculate the irreducible fraction that represents the position of both.

Start Finish Same position? Robot A: 42 105 Robot B: N D N + D = 112 0 1 5 2 5 3 5 4 5 1
Solve
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An interface designer is working on the resolution of a new screen. The aspect ratio is $16:9$ (which means that for every $16$ units of width there are $9$ of height).…

An interface designer is working on the resolution of a new screen. The aspect ratio is $16:9$ (which means that for every $16$ units of width there are $9$ of height). Draw the diagram in your notebook. If the width of the screen is defined by a number $x$ and the height by a number $y$, find the values of $x$ and $y$ knowing that:

  • $\frac{x}{y}$ is equivalent to $\frac{16}{9}$.

  • The area of the rectangle formed ($x \cdot y$) is $576$ square units.

  • $x$ and $y$ must be natural numbers.

Area = 576 u² x · y = 576 x 16 parts y 9 parts 16:9 x y = 16 9
Solve
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Find the value of the unknown $n$ so that the following fractions are equivalent: $$\frac{n-3}{20} = \frac{42}{60}$$ Once $n$ is found, find another fraction equivalent…

Find the value of the unknown $n$ so that the following fractions are equivalent:

$$\frac{n-3}{20} = \frac{42}{60}$$

Once $n$ is found, find another fraction equivalent to the previous ones whose denominator is the square of $n$. Is it possible for the numerator of this last fraction to be a prime number? Reason your answer.

Solve

Groups of fractions and common denominators

With a long list of fractions, the safest way to see which ones are equivalent is to simplify each one. Equivalent fractions have the same simplest form.

Diagram grouping the fractions 8/12, 6/9, 4/6 and 14/21, which all simplify to 2/3, apart from 10/16, which simplifies to 5/8. 8/12, 6/9, 4/6, 14/21 all simplify to 2/3 10/16 simplifies to 5/8: different

Another strategy is to rewrite fractions with a common denominator. This is especially useful when the denominator is the total of something, like points or pizza slices.

When several parts share a whole, they add up to $1$, which is $\frac{d}{d}$ for any denominator $d$. If Priya eats $\frac{6}{16}$ of a pizza and Marcus eats $\frac{10}{24}$, a common denominator of $48$ would work, but $24$ is enough once you simplify $\frac{6}{16}$ to $\frac{3}{8}$, which is $\frac{9}{24}$. So the two shares are $\frac{9}{24}$ and $\frac{10}{24}$. Marcus ate more, and $24 - 9 - 10 = 5$, so $\frac{5}{24}$ is left.

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Of the following fractions, identify which one does not belong to the group of equivalent fractions. Justify your answer by simplifying all of them to their irreducible…

Of the following fractions, identify which one does not belong to the group of equivalent fractions. Justify your answer by simplifying all of them to their irreducible fraction.

$$\dfrac{6}{10}, \dfrac{15}{25}, \dfrac{24}{40}, \dfrac{18}{32}, \dfrac{9}{15}$$
Solve
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In a strategy video game, a character's health is represented by a bar. Currently, the character has $\frac{15}{24}$ of their total health. The player consumes a potion…

In a strategy video game, a character's health is represented by a bar. Currently, the character has $\frac{15}{24}$ of their total health. The player consumes a potion that increases the current health by an amount such that the new health fraction is equivalent to $\frac{11}{12}$ of the total health.

If the denominator of the total health (the maximum capacity) is $120$ points, exactly how many health points has the character recovered with the potion? Express all the fractions in the problem with a denominator of $120$ before solving it.

15/24 Potion (?) 11/12 120 Points (TOTAL)
Solve
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Three siblings share an inheritance in the following way: the eldest receives $\frac{24}{60}$ of the total, the middle one receives a fraction equivalent to…

Three siblings share an inheritance in the following way: the eldest receives $\frac{24}{60}$ of the total, the middle one receives a fraction equivalent to $\frac{18}{45}$ and the youngest the rest.

  1. Calculate the irreducible fraction of what each of the two older siblings receives.

  2. Who receives more money, the eldest or the middle sibling?

  3. What fraction of the total does the youngest sibling receive? Is it greater or less than their siblings' shares?

Solve

Repeating decimals as fractions

Every fraction can be written as a decimal by dividing the numerator by the denominator. Some decimals end ($\frac{1}{4} = 0.25$), and some repeat forever ($\frac{1}{3} = 0.\overline{3}$). The bar marks the digits that repeat. Going back from a repeating decimal to a fraction is a nice use of equivalent fractions. Some problems call the result the generating fraction of the decimal. It is simply the number written as a fraction, then simplified.

The trick is to shift the decimal point so the repeating tails line up, then subtract them away.

Subtracting x equals 0.2727 repeating from 100x equals 27.2727 repeating leaves 99x equals 27. 100x = 27.2727… − x = 0.2727… 99x = 27, so x = 27/99 = 3/11

Once the decimals are fractions, you can compare them with everything from this page, for instance by testing whether two results are equivalent with cross-multiplication.

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Consider the pure repeating decimal $1,\widehat{36}$ and the mixed repeating decimal $1,3\widehat{6}$. 1. Find the generating fractions of both numbers and simplify them…

Consider the pure repeating decimal $1,\widehat{36}$ and the mixed repeating decimal $1,3\widehat{6}$.

  1. Find the generating fractions of both numbers and simplify them until they are irreducible.

  2. Are any of these fractions equivalent to $\frac{60}{44}$?

  3. Find a natural number by which you must multiply the denominator of the generating fraction of $1,\widehat{36}$ to obtain the denominator of the generating fraction of $1,3\widehat{6}$ as a result.

Pure Repeating 1,36 1,363636... 136 - 1 99 Mixed Repeating 1,36 1,36666... 136 - 13 90 1,360 1,365 1,370 1,3636... 1,3666...
Solve

Summary

Back to the start: Jayden has beaten $63$ levels, because $\frac{42}{60} = \frac{63}{90}$. Both cousins are at the same point in their games.

See all the exercises in this section