Subtract 28/20 from 16/21, Solve 16/21

Subtract 28/20 from 16/21

1^st number: 16/21, 2^nd number: 1 8/20

16/21 - 28/20 is -67/105.

Find the least common denominator or LCM of the two denominators:
LCM of 21 and 20 is 420

Next, find the equivalent fraction of both fractional numbers with denominator 420
For the 1st fraction, since 21 × 20 = 420,
16/21 = 16 × 20/21 × 20 = 320/420
Likewise, for the 2nd fraction, since 20 × 21 = 420,
28/20 = 28 × 21/20 × 21 = 588/420
Subtract the two like fractions:
320/420 - 588/420 = 320 - 588/420 = -268/420
After reducing the fraction, the answer is -67/105

MathStep (Works offline)

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