Subtract 8/15 from 8/21
8/21 - 8/15 is -16/105.
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,
8/21 = 8 × 5/21 × 5 = 40/105 - Likewise, for the 2nd fraction, since 15 × 7 = 105,
8/15 = 8 × 7/15 × 7 = 56/105 - Subtract the two like fractions:
40/105 - 56/105 = 40 - 56/105 = -16/105
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 16/21-8/15 8/21-16/15 8/42-8/15 8/21-8/30 24/21-8/15 8/21-24/15 8/63-8/15 8/21-8/45 40/21-8/15 8/21-40/15 8/21-8/75 56/21-8/15 8/21-56/15