Subtract 3/20 from 3/42, Solve 3/42

Subtract 3/20 from 3/42

3/42 - 3/20 is -11/140.

Find the least common denominator or LCM of the two denominators:
LCM of 42 and 20 is 420

Next, find the equivalent fraction of both fractional numbers with denominator 420
For the 1st fraction, since 42 × 10 = 420,
3/42 = 3 × 10/42 × 10 = 30/420
Likewise, for the 2nd fraction, since 20 × 21 = 420,
3/20 = 3 × 21/20 × 21 = 63/420
Subtract the two like fractions:
30/420 - 63/420 = 30 - 63/420 = -33/420
After reducing the fraction, the answer is -11/140

MathStep (Works offline)

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