Subtract 2/21 from 20/18, Solve 1 2/18

Subtract 2/21 from 20/18

1^st number: 1 2/18, 2^nd number: 2/21

20/18 - 2/21 is 64/63.

Find the least common denominator or LCM of the two denominators:
LCM of 18 and 21 is 126

Next, find the equivalent fraction of both fractional numbers with denominator 126
For the 1st fraction, since 18 × 7 = 126,
20/18 = 20 × 7/18 × 7 = 140/126
Likewise, for the 2nd fraction, since 21 × 6 = 126,
2/21 = 2 × 6/21 × 6 = 12/126
Subtract the two like fractions:
140/126 - 12/126 = 140 - 12/126 = 128/126
After reducing the fraction, the answer is 64/63
In mixed form: 11/63

MathStep (Works offline)

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