Subtract 63/42 from 45/80, Solve 45/80

Subtract 63/42 from 45/80

1^st number: 45/80, 2^nd number: 1 21/42

45/80 - 63/42 is -15/16.

Find the least common denominator or LCM of the two denominators:
LCM of 80 and 42 is 1680

Next, find the equivalent fraction of both fractional numbers with denominator 1680
For the 1st fraction, since 80 × 21 = 1680,
45/80 = 45 × 21/80 × 21 = 945/1680
Likewise, for the 2nd fraction, since 42 × 40 = 1680,
63/42 = 63 × 40/42 × 40 = 2520/1680
Subtract the two like fractions:
945/1680 - 2520/1680 = 945 - 2520/1680 = -1575/1680
After reducing the fraction, the answer is -15/16

MathStep (Works offline)

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