Subtract 21/8 from 42/9, Solve 4 6/9

Subtract 21/8 from 42/9

1^st number: 4 6/9, 2^nd number: 2 5/8

42/9 - 21/8 is 49/24.

Find the least common denominator or LCM of the two denominators:
LCM of 9 and 8 is 72

Next, find the equivalent fraction of both fractional numbers with denominator 72
For the 1st fraction, since 9 × 8 = 72,
42/9 = 42 × 8/9 × 8 = 336/72
Likewise, for the 2nd fraction, since 8 × 9 = 72,
21/8 = 21 × 9/8 × 9 = 189/72
Subtract the two like fractions:
336/72 - 189/72 = 336 - 189/72 = 147/72
After reducing the fraction, the answer is 49/24
In mixed form: 21/24

MathStep (Works offline)

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