Subtract 7/45 from 3/21
3/21 - 7/45 is -4/315.
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,
7/45 = 7 × 7/45 × 7 = 49/315 - Subtract the two like fractions:
45/315 - 49/315 = 45 - 49/315 = -4/315
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 6/21-7/45 3/21-14/45 3/42-7/45 3/21-7/90 9/21-7/45 3/21-21/45 3/63-7/45 15/21-7/45 3/21-35/45 3/21-49/45