Subtract 7/28 from 5/21
5/21 - 7/28 is -1/84.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 28 is 84
Next, find the equivalent fraction of both fractional numbers with denominator 84 - For the 1st fraction, since 21 × 4 = 84,
5/21 = 5 × 4/21 × 4 = 20/84 - Likewise, for the 2nd fraction, since 28 × 3 = 84,
7/28 = 7 × 3/28 × 3 = 21/84 - Subtract the two like fractions:
20/84 - 21/84 = 20 - 21/84 = -1/84
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 10/21-7/28 5/21-14/28 5/42-7/28 5/21-7/56 15/21-7/28 5/21-21/28 5/63-7/28 5/21-7/84 25/21-7/28 5/21-35/28 35/21-7/28 5/21-49/28