Subtract 42/8 from 21/15
1st number: 1 6/15, 2nd number: 5 2/8
21/15 - 42/8 is -77/20.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 15 and 8 is 120
Next, find the equivalent fraction of both fractional numbers with denominator 120 - For the 1st fraction, since 15 × 8 = 120,
21/15 = 21 × 8/15 × 8 = 168/120 - Likewise, for the 2nd fraction, since 8 × 15 = 120,
42/8 = 42 × 15/8 × 15 = 630/120 - Subtract the two like fractions:
168/120 - 630/120 = 168 - 630/120 = -462/120 - After reducing the fraction, the answer is -77/20
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/15-42/8 21/15-84/8 21/30-42/8 21/15-42/16 63/15-42/8 21/45-42/8 21/15-42/24 21/75-42/8 21/15-42/40 21/15-42/56