Subtract 4/40 from 15/21, Solve 15/21

Subtract 4/40 from 15/21

15/21 - 4/40 is 43/70.

Find the least common denominator or LCM of the two denominators:
LCM of 21 and 40 is 840

Next, find the equivalent fraction of both fractional numbers with denominator 840
For the 1st fraction, since 21 × 40 = 840,
15/21 = 15 × 40/21 × 40 = 600/840
Likewise, for the 2nd fraction, since 40 × 21 = 840,
4/40 = 4 × 21/40 × 21 = 84/840
Subtract the two like fractions:
600/840 - 84/840 = 600 - 84/840 = 516/840
After reducing the fraction, the answer is 43/70

MathStep (Works offline)

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