Subtract 20/7 from 21/30
1st number: 21/30, 2nd number: 2 6/7
21/30 - 20/7 is -151/70.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 30 and 7 is 210
Next, find the equivalent fraction of both fractional numbers with denominator 210 - For the 1st fraction, since 30 × 7 = 210,
21/30 = 21 × 7/30 × 7 = 147/210 - Likewise, for the 2nd fraction, since 7 × 30 = 210,
20/7 = 20 × 30/7 × 30 = 600/210 - Subtract the two like fractions:
147/210 - 600/210 = 147 - 600/210 = -453/210 - After reducing the fraction, the answer is -151/70
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/30-20/7 21/30-40/7 21/60-20/7 21/30-20/14 63/30-20/7 21/30-60/7 21/90-20/7 21/30-20/21 21/30-20/35 21/30-20/49