Subtract 72/18 from 7/42, Solve 7/42

Subtract 72/18 from 7/42

1^st number: 7/42, 2^nd number: 4 0/18

7/42 - 72/18 is -23/6.

Find the least common denominator or LCM of the two denominators:
LCM of 42 and 18 is 126

Next, find the equivalent fraction of both fractional numbers with denominator 126
For the 1st fraction, since 42 × 3 = 126,
7/42 = 7 × 3/42 × 3 = 21/126
Likewise, for the 2nd fraction, since 18 × 7 = 126,
72/18 = 72 × 7/18 × 7 = 504/126
Subtract the two like fractions:
21/126 - 504/126 = 21 - 504/126 = -483/126
After reducing the fraction, the answer is -23/6

MathStep (Works offline)

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