Subtract 54/7 from 21/30, Solve 21/30

Subtract 54/7 from 21/30

1^st number: 21/30, 2^nd number: 7 5/7

21/30 - 54/7 is -491/70.

Find the least common denominator or LCM of the two denominators:
LCM of 30 and 7 is 210

Next, find the equivalent fraction of both fractional numbers with denominator 210
For the 1st fraction, since 30 × 7 = 210,
21/30 = 21 × 7/30 × 7 = 147/210
Likewise, for the 2nd fraction, since 7 × 30 = 210,
54/7 = 54 × 30/7 × 30 = 1620/210
Subtract the two like fractions:
147/210 - 1620/210 = 147 - 1620/210 = -1473/210
After reducing the fraction, the answer is -491/70

MathStep (Works offline)

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