Subtract 12/15 from 21/28
21/28 - 12/15 is -1/20.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 28 and 15 is 420
Next, find the equivalent fraction of both fractional numbers with denominator 420 - For the 1st fraction, since 28 × 15 = 420,
21/28 = 21 × 15/28 × 15 = 315/420 - Likewise, for the 2nd fraction, since 15 × 28 = 420,
12/15 = 12 × 28/15 × 28 = 336/420 - Subtract the two like fractions:
315/420 - 336/420 = 315 - 336/420 = -21/420 - After reducing the fraction, the answer is -1/20
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/28-12/15 21/28-24/15 21/56-12/15 21/28-12/30 63/28-12/15 21/28-36/15 21/84-12/15 21/28-12/45 21/28-60/15 21/28-12/75 21/28-84/15