Subtract 42/21 from 7/15
1st number: 7/15, 2nd number: 2 0/21
7/15 - 42/21 is -23/15.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 15 and 21 is 105
Next, find the equivalent fraction of both fractional numbers with denominator 105 - For the 1st fraction, since 15 × 7 = 105,
7/15 = 7 × 7/15 × 7 = 49/105 - Likewise, for the 2nd fraction, since 21 × 5 = 105,
42/21 = 42 × 5/21 × 5 = 210/105 - Subtract the two like fractions:
49/105 - 210/105 = 49 - 210/105 = -161/105 - After reducing the fraction, the answer is -23/15
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 14/15-42/21 7/15-84/21 7/30-42/21 21/15-42/21 7/45-42/21 7/15-42/63 35/15-42/21 7/75-42/21 49/15-42/21