Subtract 81/20 from 90/70
1st number: 1 20/70, 2nd number: 4 1/20
90/70 - 81/20 is -387/140.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 70 and 20 is 140
Next, find the equivalent fraction of both fractional numbers with denominator 140 - For the 1st fraction, since 70 × 2 = 140,
90/70 = 90 × 2/70 × 2 = 180/140 - Likewise, for the 2nd fraction, since 20 × 7 = 140,
81/20 = 81 × 7/20 × 7 = 567/140 - Subtract the two like fractions:
180/140 - 567/140 = 180 - 567/140 = -387/140
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 90/70-81/40 90/70-81/60