Subtract 9/20 from 63/21, Solve 3 0/21

Subtract 9/20 from 63/21

1^st number: 3 0/21, 2^nd number: 9/20

63/21 - 9/20 is 51/20.

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,
63/21 = 63 × 20/21 × 20 = 1260/420
Likewise, for the 2nd fraction, since 20 × 21 = 420,
9/20 = 9 × 21/20 × 21 = 189/420
Subtract the two like fractions:
1260/420 - 189/420 = 1260 - 189/420 = 1071/420
After reducing the fraction, the answer is 51/20
In mixed form: 211/20

MathStep (Works offline)

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