Subtract 27/72 from 3/21, Solve 3/21

Subtract 27/72 from 3/21

3/21 - 27/72 is -13/56.

Find the least common denominator or LCM of the two denominators:
LCM of 21 and 72 is 504

Next, find the equivalent fraction of both fractional numbers with denominator 504
For the 1st fraction, since 21 × 24 = 504,
3/21 = 3 × 24/21 × 24 = 72/504
Likewise, for the 2nd fraction, since 72 × 7 = 504,
27/72 = 27 × 7/72 × 7 = 189/504
Subtract the two like fractions:
72/504 - 189/504 = 72 - 189/504 = -117/504
After reducing the fraction, the answer is -13/56

MathStep (Works offline)

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