Subtract 21/28 from 18/42
18/42 - 21/28 is -9/28.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 42 and 28 is 84
Next, find the equivalent fraction of both fractional numbers with denominator 84 - For the 1st fraction, since 42 × 2 = 84,
18/42 = 18 × 2/42 × 2 = 36/84 - Likewise, for the 2nd fraction, since 28 × 3 = 84,
21/28 = 21 × 3/28 × 3 = 63/84 - Subtract the two like fractions:
36/84 - 63/84 = 36 - 63/84 = -27/84 - After reducing the fraction, the answer is -9/28
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 36/42-21/28 18/42-42/28 18/84-21/28 18/42-21/56 54/42-21/28 18/42-63/28 18/42-21/84 90/42-21/28