Subtract 72/21 from 3/12
1st number: 3/12, 2nd number: 3 9/21
3/12 - 72/21 is -89/28.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 12 and 21 is 84
Next, find the equivalent fraction of both fractional numbers with denominator 84 - For the 1st fraction, since 12 × 7 = 84,
3/12 = 3 × 7/12 × 7 = 21/84 - Likewise, for the 2nd fraction, since 21 × 4 = 84,
72/21 = 72 × 4/21 × 4 = 288/84 - Subtract the two like fractions:
21/84 - 288/84 = 21 - 288/84 = -267/84 - After reducing the fraction, the answer is -89/28
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 6/12-72/21 3/24-72/21 3/12-72/42 9/12-72/21 3/36-72/21 3/12-72/63 15/12-72/21 3/60-72/21 21/12-72/21 3/84-72/21