Subtract 81/84 from 42/40, Solve 1 2/40

Subtract 81/84 from 42/40

1^st number: 1 2/40, 2^nd number: 81/84

42/40 - 81/84 is 3/35.

Find the least common denominator or LCM of the two denominators:
LCM of 40 and 84 is 840

Next, find the equivalent fraction of both fractional numbers with denominator 840
For the 1st fraction, since 40 × 21 = 840,
42/40 = 42 × 21/40 × 21 = 882/840
Likewise, for the 2nd fraction, since 84 × 10 = 840,
81/84 = 81 × 10/84 × 10 = 810/840
Subtract the two like fractions:
882/840 - 810/840 = 882 - 810/840 = 72/840
After reducing the fraction, the answer is 3/35

MathStep (Works offline)

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