Subtracting fractions

Subtracting fractions is easier than you think since it is very similar to adding fractions. Just like adding fractions, there are two important things you need to know:

Subtracting fractions
  • First, you cannot subtract the denominators; you can only subtract the numerators.
  • Second, you can only subtract the numerators when the denominator is the same for both fractions. Your denominator will stay the same.
Having said that, just like adding fractions, if the denominators are different, you will first find equivalent fractions that give a common denominator for both fractions.

More examples about subtracting fractions


Example #1:

5 / 2
 − 
1 / 2
= ?

There is no need to look for a common denominator because they are already the same.

So,  
5 / 2
 − 
1 / 2
 = 
5 − 1 / 2
 = 
4 / 2
= 2

Example #2:

7 / 3
 − 
3 / 6
= ?

Here the denominators are not the same, so multiply 3 by 2 to get the same denominator.

Remember that we have to multiply 7 by 2 also in order not to change the problem.

So,  
7 / 3
 − 
3 / 6
 = 
7 × 2 / 3 × 2
 − 
3 / 6
 = 
14 / 6
 − 
3 / 6
 = 
11 / 6

Example #3:

3 / 5
 − 
2 / 4
= ?


So,  
3 / 5
 − 
2 / 4
 = 
3 × 4 / 5 × 4
 − 
2 × 5 / 4 × 5
 = 
12 / 20
 − 
10 / 20
 = 
2 / 20


5 / 2
 − 
1 / 2
= ?

There is no need to look for a common denominator because they are already the same.

So,  
5 / 2
 − 
1 / 2
 = 
5 − 1 / 2
 = 
4 / 2
= 2

Example #2:

7 / 3
 − 
3 / 6
= ?

Here the denominators are not the same, so multiply 3 by 2 to get the same denominator.

Remember that we have to multiply 7 by 2 also in order not to change the problem.

So,  
7 / 3
 − 
3 / 6
 = 
7 × 2 / 3 × 2
 − 
3 / 6

7 / 3
 − 
3 / 6
 = 
14 / 6
 − 
3 / 6
 = 
11 / 6

Example #3:

3 / 5
 − 
2 / 4
= ?


So,  
3 / 5
 − 
2 / 4
 = 
3 × 4 / 5 × 4
 − 
2 × 5 / 4 × 5

3 / 5
 − 
2 / 4
 = 
12 / 20
 − 
10 / 20
 = 
2 / 20

Subtracting fractions quiz. See how well you can subtract fractions.

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