Subtract 30/42 from 42/90, Solve 42/90

Subtract 30/42 from 42/90

42/90 - 30/42 is -26/105.

Find the least common denominator or LCM of the two denominators:
LCM of 90 and 42 is 630

Next, find the equivalent fraction of both fractional numbers with denominator 630
For the 1st fraction, since 90 × 7 = 630,
42/90 = 42 × 7/90 × 7 = 294/630
Likewise, for the 2nd fraction, since 42 × 15 = 630,
30/42 = 30 × 15/42 × 15 = 450/630
Subtract the two like fractions:
294/630 - 450/630 = 294 - 450/630 = -156/630
After reducing the fraction, the answer is -26/105

MathStep (Works offline)

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