Question

How to subtract fractions with unlike denominators khan academy?

Answer 1

First find the LCD of the denominators  then convert the fractions. Then you can subtract.

for example

2/7 - 1/4

LCD of 4 and 7 is 28 so we convert to fractions with denominator 28

1/4  = 1*7 / 4*7  = 7 /28

2/7  = 2*4 / 7*4 = 8/28


so 2/7 - 1/4  = 8 /28 / 7/28  = 1/28 answer