Subtract 15/20 from 5/21
5/21 - 15/20 is -43/84.
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,
5/21 = 5 × 20/21 × 20 = 100/420 - Likewise, for the 2nd fraction, since 20 × 21 = 420,
15/20 = 15 × 21/20 × 21 = 315/420 - Subtract the two like fractions:
100/420 - 315/420 = 100 - 315/420 = -215/420 - After reducing the fraction, the answer is -43/84
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 10/21-15/20 5/21-30/20 5/42-15/20 5/21-15/40 15/21-15/20 5/21-45/20 5/63-15/20 5/21-15/60 25/21-15/20 5/21-75/20 35/21-15/20