Subtract 15/42 from 21/70
21/70 - 15/42 is -2/35.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 70 and 42 is 210
Next, find the equivalent fraction of both fractional numbers with denominator 210 - For the 1st fraction, since 70 × 3 = 210,
21/70 = 21 × 3/70 × 3 = 63/210 - Likewise, for the 2nd fraction, since 42 × 5 = 210,
15/42 = 15 × 5/42 × 5 = 75/210 - Subtract the two like fractions:
63/210 - 75/210 = 63 - 75/210 = -12/210 - After reducing the fraction, the answer is -2/35
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/70-15/42 21/70-30/42 21/70-15/84 63/70-15/42 21/70-45/42 21/70-75/42