Subtract 5/40 from 4/42, Solve 4/42

Subtract 5/40 from 4/42

4/42 - 5/40 is -5/168.

Find the least common denominator or LCM of the two denominators:
LCM of 42 and 40 is 840

Next, find the equivalent fraction of both fractional numbers with denominator 840
For the 1st fraction, since 42 × 20 = 840,
4/42 = 4 × 20/42 × 20 = 80/840
Likewise, for the 2nd fraction, since 40 × 21 = 840,
5/40 = 5 × 21/40 × 21 = 105/840
Subtract the two like fractions:
80/840 - 105/840 = 80 - 105/840 = -25/840
After reducing the fraction, the answer is -5/168

MathStep (Works offline)

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