Subtract 42/49 from 15/21
15/21 - 42/49 is -1/7.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 49 is 147
Next, find the equivalent fraction of both fractional numbers with denominator 147 - For the 1st fraction, since 21 × 7 = 147,
15/21 = 15 × 7/21 × 7 = 105/147 - Likewise, for the 2nd fraction, since 49 × 3 = 147,
42/49 = 42 × 3/49 × 3 = 126/147 - Subtract the two like fractions:
105/147 - 126/147 = 105 - 126/147 = -21/147 - After reducing the fraction, the answer is -1/7
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 30/21-42/49 15/21-84/49 15/42-42/49 15/21-42/98 45/21-42/49 15/63-42/49 75/21-42/49