Subtract 21/27 from 7/40, Solve 7/40

Subtract 21/27 from 7/40

7/40 - 21/27 is -217/360.

Find the least common denominator or LCM of the two denominators:
LCM of 40 and 27 is 1080

Next, find the equivalent fraction of both fractional numbers with denominator 1080
For the 1st fraction, since 40 × 27 = 1080,
7/40 = 7 × 27/40 × 27 = 189/1080
Likewise, for the 2nd fraction, since 27 × 40 = 1080,
21/27 = 21 × 40/27 × 40 = 840/1080
Subtract the two like fractions:
189/1080 - 840/1080 = 189 - 840/1080 = -651/1080
After reducing the fraction, the answer is -217/360

MathStep (Works offline)

Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad