Subtract 90/21 from 72/28
1st number: 2 16/28, 2nd number: 4 6/21
72/28 - 90/21 is -12/7.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 28 and 21 is 84
Next, find the equivalent fraction of both fractional numbers with denominator 84 - For the 1st fraction, since 28 × 3 = 84,
72/28 = 72 × 3/28 × 3 = 216/84 - Likewise, for the 2nd fraction, since 21 × 4 = 84,
90/21 = 90 × 4/21 × 4 = 360/84 - Subtract the two like fractions:
216/84 - 360/84 = 216 - 360/84 = -144/84 - After reducing the fraction, the answer is -12/7
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 72/56-90/21 72/28-90/42 72/84-90/21 72/28-90/63