Subtract 5/40 from 8/21, Solve 8/21

Subtract 5/40 from 8/21

8/21 - 5/40 is 43/168.

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,
8/21 = 8 × 40/21 × 40 = 320/840
Likewise, for the 2nd fraction, since 40 × 21 = 840,
5/40 = 5 × 21/40 × 21 = 105/840
Subtract the two like fractions:
320/840 - 105/840 = 320 - 105/840 = 215/840
After reducing the fraction, the answer is 43/168

MathStep (Works offline)

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