Subtract 21/27 from 18/28
18/28 - 21/27 is -17/126.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 28 and 27 is 756
Next, find the equivalent fraction of both fractional numbers with denominator 756 - For the 1st fraction, since 28 × 27 = 756,
18/28 = 18 × 27/28 × 27 = 486/756 - Likewise, for the 2nd fraction, since 27 × 28 = 756,
21/27 = 21 × 28/27 × 28 = 588/756 - Subtract the two like fractions:
486/756 - 588/756 = 486 - 588/756 = -102/756 - After reducing the fraction, the answer is -17/126
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 36/28-21/27 18/28-42/27 18/56-21/27 18/28-21/54 54/28-21/27 18/28-63/27 18/84-21/27 18/28-21/81 90/28-21/27