Subtract 30/15 from 15/21
1st number: 15/21, 2nd number: 2 0/15
15/21 - 30/15 is -9/7.
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,
15/21 = 15 × 5/21 × 5 = 75/105 - Likewise, for the 2nd fraction, since 15 × 7 = 105,
30/15 = 30 × 7/15 × 7 = 210/105 - Subtract the two like fractions:
75/105 - 210/105 = 75 - 210/105 = -135/105 - After reducing the fraction, the answer is -9/7
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 30/21-30/15 15/21-60/15 15/42-30/15 45/21-30/15 15/21-90/15 15/63-30/15 15/21-30/45 75/21-30/15 15/21-30/75