Subtract 42/12 from 1/90, Solve 1/90

Subtract 42/12 from 1/90

1^st number: 1/90, 2^nd number: 3 6/12

1/90 - 42/12 is -157/45.

Find the least common denominator or LCM of the two denominators:
LCM of 90 and 12 is 180

Next, find the equivalent fraction of both fractional numbers with denominator 180
For the 1st fraction, since 90 × 2 = 180,
1/90 = 1 × 2/90 × 2 = 2/180
Likewise, for the 2nd fraction, since 12 × 15 = 180,
42/12 = 42 × 15/12 × 15 = 630/180
Subtract the two like fractions:
2/180 - 630/180 = 2 - 630/180 = -628/180
After reducing the fraction, the answer is -157/45

MathStep (Works offline)

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