How do you subtract unlike fractions?
Mathematics · Middle School · Tue Nov 03 2020
Answered on
To subtract unlike fractions, we first convert them into like fractions. In order to make a common denominator, we find LCM of all the different denominators of given fractions and then make them equivalent fractions with a common denominators.
For example:- Subtract 4/9 from 5/7.
Solution: 5/7 - 4/9
The L.C.M. of the denominators 9 and 7 is 63.
and to make denominator same we have to multiply 5/7 by 9 /9 and similarly 4/9 by 7/7
5/7 = (5/7)*(9/ 9) = 45/63, (because 63 ÷ 7 = 9)
4/9 = (4 /9)*(7/ 7) = 28/63, (because 63 ÷ 9 = 7)
Thus, 5/7 - 4/9
= 45/63 - 28/63
= (45 - 28)/63
= 17/63