Subtract 15/45 from 3/21
3/21 - 15/45 is -4/21.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 45 is 315
Next, find the equivalent fraction of both fractional numbers with denominator 315 - For the 1st fraction, since 21 × 15 = 315,
3/21 = 3 × 15/21 × 15 = 45/315 - Likewise, for the 2nd fraction, since 45 × 7 = 315,
15/45 = 15 × 7/45 × 7 = 105/315 - Subtract the two like fractions:
45/315 - 105/315 = 45 - 105/315 = -60/315 - After reducing the fraction, the answer is -4/21
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 6/21-15/45 3/21-30/45 3/42-15/45 3/21-15/90 9/21-15/45 3/63-15/45 15/21-15/45 3/21-75/45