Subtract 42/12 from 21/25, Solve 21/25

Subtract 42/12 from 21/25

1^st number: 21/25, 2^nd number: 3 6/12

21/25 - 42/12 is -133/50.

Find the least common denominator or LCM of the two denominators:
LCM of 25 and 12 is 300

Next, find the equivalent fraction of both fractional numbers with denominator 300
For the 1st fraction, since 25 × 12 = 300,
21/25 = 21 × 12/25 × 12 = 252/300
Likewise, for the 2nd fraction, since 12 × 25 = 300,
42/12 = 42 × 25/12 × 25 = 1050/300
Subtract the two like fractions:
252/300 - 1050/300 = 252 - 1050/300 = -798/300
After reducing the fraction, the answer is -133/50

MathStep (Works offline)

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