Subtract 21/70 from 42/72
42/72 - 21/70 is 17/60.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 72 and 70 is 2520
Next, find the equivalent fraction of both fractional numbers with denominator 2520 - For the 1st fraction, since 72 × 35 = 2520,
42/72 = 42 × 35/72 × 35 = 1470/2520 - Likewise, for the 2nd fraction, since 70 × 36 = 2520,
21/70 = 21 × 36/70 × 36 = 756/2520 - Subtract the two like fractions:
1470/2520 - 756/2520 = 1470 - 756/2520 = 714/2520 - After reducing the fraction, the answer is 17/60
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 84/72-21/70 42/72-42/70 42/72-63/70