Subtract 5/42 from 18/21
18/21 - 5/42 is 31/42.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 42 is 42
Next, find the equivalent fraction of both fractional numbers with denominator 42 - For the 1st fraction, since 21 × 2 = 42,
18/21 = 18 × 2/21 × 2 = 36/42 - Likewise, for the 2nd fraction, since 42 × 1 = 42,
5/42 = 5 × 1/42 × 1 = 5/42 - Subtract the two like fractions:
36/42 - 5/42 = 36 - 5/42 = 31/42
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 36/21-5/42 18/21-10/42 18/42-5/42 18/21-5/84 54/21-5/42 18/21-15/42 18/63-5/42 90/21-5/42 18/21-25/42 18/21-35/42