Subtract 9/20 from 7/21
7/21 - 9/20 is -7/60.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 20 is 420
Next, find the equivalent fraction of both fractional numbers with denominator 420 - For the 1st fraction, since 21 × 20 = 420,
7/21 = 7 × 20/21 × 20 = 140/420 - Likewise, for the 2nd fraction, since 20 × 21 = 420,
9/20 = 9 × 21/20 × 21 = 189/420 - Subtract the two like fractions:
140/420 - 189/420 = 140 - 189/420 = -49/420 - After reducing the fraction, the answer is -7/60
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 14/21-9/20 7/21-18/20 7/42-9/20 7/21-9/40 7/21-27/20 7/63-9/20 7/21-9/60 35/21-9/20 7/21-45/20 49/21-9/20 7/21-63/20