Subtract 40/54 from 81/21, Solve 3 18/21

Subtract 40/54 from 81/21

1^st number: 3 18/21, 2^nd number: 40/54

81/21 - 40/54 is 589/189.

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,
81/21 = 81 × 18/21 × 18 = 1458/378
Likewise, for the 2nd fraction, since 54 × 7 = 378,
40/54 = 40 × 7/54 × 7 = 280/378
Subtract the two like fractions:
1458/378 - 280/378 = 1458 - 280/378 = 1178/378
After reducing the fraction, the answer is 589/189
In mixed form: 322/189

MathStep (Works offline)

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