Subtract 90/80 from 20/42
1st number: 20/42, 2nd number: 1 10/80
20/42 - 90/80 is -109/168.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 42 and 80 is 1680
Next, find the equivalent fraction of both fractional numbers with denominator 1680 - For the 1st fraction, since 42 × 40 = 1680,
20/42 = 20 × 40/42 × 40 = 800/1680 - Likewise, for the 2nd fraction, since 80 × 21 = 1680,
90/80 = 90 × 21/80 × 21 = 1890/1680 - Subtract the two like fractions:
800/1680 - 1890/1680 = 800 - 1890/1680 = -1090/1680 - After reducing the fraction, the answer is -109/168
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 40/42-90/80 20/84-90/80 60/42-90/80