Subtract 30/10 from 20/42, Solve 20/42

Subtract 30/10 from 20/42

1^st number: 20/42, 2^nd number: 3 0/10

20/42 - 30/10 is -53/21.

Find the least common denominator or LCM of the two denominators:
LCM of 42 and 10 is 210

Next, find the equivalent fraction of both fractional numbers with denominator 210
For the 1st fraction, since 42 × 5 = 210,
20/42 = 20 × 5/42 × 5 = 100/210
Likewise, for the 2nd fraction, since 10 × 21 = 210,
30/10 = 30 × 21/10 × 21 = 630/210
Subtract the two like fractions:
100/210 - 630/210 = 100 - 630/210 = -530/210
After reducing the fraction, the answer is -53/21

MathStep (Works offline)

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