Subtract 5/70 from 21/54, Solve 21/54

Subtract 5/70 from 21/54

21/54 - 5/70 is 20/63.

Find the least common denominator or LCM of the two denominators:
LCM of 54 and 70 is 1890

Next, find the equivalent fraction of both fractional numbers with denominator 1890
For the 1st fraction, since 54 × 35 = 1890,
21/54 = 21 × 35/54 × 35 = 735/1890
Likewise, for the 2nd fraction, since 70 × 27 = 1890,
5/70 = 5 × 27/70 × 27 = 135/1890
Subtract the two like fractions:
735/1890 - 135/1890 = 735 - 135/1890 = 600/1890
After reducing the fraction, the answer is 20/63

MathStep (Works offline)

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