Subtract 30/54 from 70/21, Solve 3 7/21

Subtract 30/54 from 70/21

1^st number: 3 7/21, 2^nd number: 30/54

70/21 - 30/54 is 25/9.

Find the least common denominator or LCM of the two denominators:
LCM of 21 and 54 is 378

Next, find the equivalent fraction of both fractional numbers with denominator 378
For the 1st fraction, since 21 × 18 = 378,
70/21 = 70 × 18/21 × 18 = 1260/378
Likewise, for the 2nd fraction, since 54 × 7 = 378,
30/54 = 30 × 7/54 × 7 = 210/378
Subtract the two like fractions:
1260/378 - 210/378 = 1260 - 210/378 = 1050/378
After reducing the fraction, the answer is 25/9
In mixed form: 27/9

MathStep (Works offline)

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