Subtract 30/9 from 15/21
1st number: 15/21, 2nd number: 3 3/9
15/21 - 30/9 is -55/21.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 9 is 63
Next, find the equivalent fraction of both fractional numbers with denominator 63 - For the 1st fraction, since 21 × 3 = 63,
15/21 = 15 × 3/21 × 3 = 45/63 - Likewise, for the 2nd fraction, since 9 × 7 = 63,
30/9 = 30 × 7/9 × 7 = 210/63 - Subtract the two like fractions:
45/63 - 210/63 = 45 - 210/63 = -165/63 - After reducing the fraction, the answer is -55/21
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 30/21-30/9 15/21-60/9 15/42-30/9 15/21-30/18 45/21-30/9 15/21-90/9 15/63-30/9 15/21-30/27 75/21-30/9 15/21-30/45 15/21-30/63