Subtract 18/15 from 3/21
1st number: 3/21, 2nd number: 1 3/15
3/21 - 18/15 is -37/35.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 15 is 105
Next, find the equivalent fraction of both fractional numbers with denominator 105 - For the 1st fraction, since 21 × 5 = 105,
3/21 = 3 × 5/21 × 5 = 15/105 - Likewise, for the 2nd fraction, since 15 × 7 = 105,
18/15 = 18 × 7/15 × 7 = 126/105 - Subtract the two like fractions:
15/105 - 126/105 = 15 - 126/105 = -111/105 - After reducing the fraction, the answer is -37/35
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 6/21-18/15 3/21-36/15 3/42-18/15 3/21-18/30 9/21-18/15 3/21-54/15 3/63-18/15 3/21-18/45 15/21-18/15 3/21-90/15 3/21-18/75