Subtract 70/18 from 72/21
1st number: 3 9/21, 2nd number: 3 16/18
72/21 - 70/18 is -29/63.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 18 is 126
Next, find the equivalent fraction of both fractional numbers with denominator 126 - For the 1st fraction, since 21 × 6 = 126,
72/21 = 72 × 6/21 × 6 = 432/126 - Likewise, for the 2nd fraction, since 18 × 7 = 126,
70/18 = 70 × 7/18 × 7 = 490/126 - Subtract the two like fractions:
432/126 - 490/126 = 432 - 490/126 = -58/126 - After reducing the fraction, the answer is -29/63
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 72/42-70/18 72/21-70/36 72/63-70/18 72/21-70/54 72/21-70/90