Subtract 45/10 from 21/28, Solve 21/28

Subtract 45/10 from 21/28

1^st number: 21/28, 2^nd number: 4 5/10

21/28 - 45/10 is -15/4.

Find the least common denominator or LCM of the two denominators:
LCM of 28 and 10 is 140

Next, find the equivalent fraction of both fractional numbers with denominator 140
For the 1st fraction, since 28 × 5 = 140,
21/28 = 21 × 5/28 × 5 = 105/140
Likewise, for the 2nd fraction, since 10 × 14 = 140,
45/10 = 45 × 14/10 × 14 = 630/140
Subtract the two like fractions:
105/140 - 630/140 = 105 - 630/140 = -525/140
After reducing the fraction, the answer is -15/4

MathStep (Works offline)

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