Subtract 72/21 from 81/24
1st number: 3 9/24, 2nd number: 3 9/21
81/24 - 72/21 is -3/56.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 24 and 21 is 168
Next, find the equivalent fraction of both fractional numbers with denominator 168 - For the 1st fraction, since 24 × 7 = 168,
81/24 = 81 × 7/24 × 7 = 567/168 - Likewise, for the 2nd fraction, since 21 × 8 = 168,
72/21 = 72 × 8/21 × 8 = 576/168 - Subtract the two like fractions:
567/168 - 576/168 = 567 - 576/168 = -9/168 - After reducing the fraction, the answer is -3/56
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 81/48-72/21 81/24-72/42 81/72-72/21 81/24-72/63