Subtract 90/70 from 10/21
1st number: 10/21, 2nd number: 1 20/70
10/21 - 90/70 is -17/21.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 70 is 210
Next, find the equivalent fraction of both fractional numbers with denominator 210 - For the 1st fraction, since 21 × 10 = 210,
10/21 = 10 × 10/21 × 10 = 100/210 - Likewise, for the 2nd fraction, since 70 × 3 = 210,
90/70 = 90 × 3/70 × 3 = 270/210 - Subtract the two like fractions:
100/210 - 270/210 = 100 - 270/210 = -170/210 - After reducing the fraction, the answer is -17/21
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 20/21-90/70 10/42-90/70 30/21-90/70 10/63-90/70 50/21-90/70 70/21-90/70