Subtract 21/15 from 18/30
1st number: 18/30, 2nd number: 1 6/15
18/30 - 21/15 is -4/5.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 30 and 15 is 30
Next, find the equivalent fraction of both fractional numbers with denominator 30 - For the 1st fraction, since 30 × 1 = 30,
18/30 = 18 × 1/30 × 1 = 18/30 - Likewise, for the 2nd fraction, since 15 × 2 = 30,
21/15 = 21 × 2/15 × 2 = 42/30 - Subtract the two like fractions:
18/30 - 42/30 = 18 - 42/30 = -24/30 - After reducing the fraction, the answer is -4/5
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 36/30-21/15 18/30-42/15 18/60-21/15 18/30-21/30 54/30-21/15 18/30-63/15 18/90-21/15 18/30-21/45 90/30-21/15 18/30-21/75