Subtract 8/21 from 21/28
21/28 - 8/21 is 31/84.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 28 and 21 is 84
Next, find the equivalent fraction of both fractional numbers with denominator 84 - For the 1st fraction, since 28 × 3 = 84,
21/28 = 21 × 3/28 × 3 = 63/84 - Likewise, for the 2nd fraction, since 21 × 4 = 84,
8/21 = 8 × 4/21 × 4 = 32/84 - Subtract the two like fractions:
63/84 - 32/84 = 63 - 32/84 = 31/84
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/28-8/21 21/28-16/21 21/56-8/21 21/28-8/42 63/28-8/21 21/28-24/21 21/84-8/21 21/28-8/63 21/28-40/21 21/28-56/21