Subtract 10/20 from 30/21, Solve 1 9/21

Subtract 10/20 from 30/21

1^st number: 1 9/21, 2^nd number: 10/20

30/21 - 10/20 is 13/14.

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,
30/21 = 30 × 20/21 × 20 = 600/420
Likewise, for the 2nd fraction, since 20 × 21 = 420,
10/20 = 10 × 21/20 × 21 = 210/420
Subtract the two like fractions:
600/420 - 210/420 = 600 - 210/420 = 390/420
After reducing the fraction, the answer is 13/14

MathStep (Works offline)

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