Subtract 3/42 from 20/8, Solve 2 4/8

Subtract 3/42 from 20/8

1^st number: 2 4/8, 2^nd number: 3/42

20/8 - 3/42 is 17/7.

Find the least common denominator or LCM of the two denominators:
LCM of 8 and 42 is 168

Next, find the equivalent fraction of both fractional numbers with denominator 168
For the 1st fraction, since 8 × 21 = 168,
20/8 = 20 × 21/8 × 21 = 420/168
Likewise, for the 2nd fraction, since 42 × 4 = 168,
3/42 = 3 × 4/42 × 4 = 12/168
Subtract the two like fractions:
420/168 - 12/168 = 420 - 12/168 = 408/168
After reducing the fraction, the answer is 17/7
In mixed form: 23/7

MathStep (Works offline)

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