Subtract 15/7 from 30/21
1st number: 1 9/21, 2nd number: 2 1/7
30/21 - 15/7 is -5/7.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 7 is 21
Next, find the equivalent fraction of both fractional numbers with denominator 21 - For the 1st fraction, since 21 × 1 = 21,
30/21 = 30 × 1/21 × 1 = 30/21 - Likewise, for the 2nd fraction, since 7 × 3 = 21,
15/7 = 15 × 3/7 × 3 = 45/21 - Subtract the two like fractions:
30/21 - 45/21 = 30 - 45/21 = -15/21 - After reducing the fraction, the answer is -5/7
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 60/21-15/7 30/21-30/7 30/42-15/7 30/21-15/14 90/21-15/7 30/21-45/7 30/63-15/7 30/21-15/21 30/21-75/7 30/21-15/35 30/21-15/49