Subtract 60/42 from 90/80, Solve 1 10/80

Subtract 60/42 from 90/80

1^st number: 1 10/80, 2^nd number: 1 18/42

90/80 - 60/42 is -17/56.

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,
90/80 = 90 × 21/80 × 21 = 1890/1680
Likewise, for the 2nd fraction, since 42 × 40 = 1680,
60/42 = 60 × 40/42 × 40 = 2400/1680
Subtract the two like fractions:
1890/1680 - 2400/1680 = 1890 - 2400/1680 = -510/1680
After reducing the fraction, the answer is -17/56

MathStep (Works offline)

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