Subtract 25/70 from 21/18, Solve 1 3/18

Subtract 25/70 from 21/18

1^st number: 1 3/18, 2^nd number: 25/70

21/18 - 25/70 is 17/21.

Find the least common denominator or LCM of the two denominators:
LCM of 18 and 70 is 630

Next, find the equivalent fraction of both fractional numbers with denominator 630
For the 1st fraction, since 18 × 35 = 630,
21/18 = 21 × 35/18 × 35 = 735/630
Likewise, for the 2nd fraction, since 70 × 9 = 630,
25/70 = 25 × 9/70 × 9 = 225/630
Subtract the two like fractions:
735/630 - 225/630 = 735 - 225/630 = 510/630
After reducing the fraction, the answer is 17/21

MathStep (Works offline)

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