Subtracting Fractions with Different Denominators

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You can subtract fractions only if they have the same denominator, so you must first change each of the two fractions to a common denominator.

Example 1 Suppose you have two fractions 2/3 and 1/4 to be subtracted:

2		1
---	-	---	=	---
3		4

Select the denominator of the second fraction (4) and multiply thedenominator and numerator of first fraction (2/3) by that number:

2		4		8
---	x	---	=	---
3		4		12

Select the denominator of the first fraction (3) and multiply the numerator and denominator of the second fraction (1/4) by that number:

1		3		3
---	-	---	=	---
4		3		12

Now use the fractions with the common denominators and subtract the numerators. Do Not subtract the denominators.

8		3		5
---	-	---	=	---
12		12		12

You may need to reduce to lowest terms.

The correct answer in lowest terms is 5/12.

Good luck in subtracting fractions with different denominators.