Subtract 90/72 from 5/21
1st number: 5/21, 2nd number: 1 18/72
5/21 - 90/72 is -85/84.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 72 is 504
Next, find the equivalent fraction of both fractional numbers with denominator 504 - For the 1st fraction, since 21 × 24 = 504,
5/21 = 5 × 24/21 × 24 = 120/504 - Likewise, for the 2nd fraction, since 72 × 7 = 504,
90/72 = 90 × 7/72 × 7 = 630/504 - Subtract the two like fractions:
120/504 - 630/504 = 120 - 630/504 = -510/504 - After reducing the fraction, the answer is -85/84
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 10/21-90/72 5/42-90/72 15/21-90/72 5/63-90/72 25/21-90/72 35/21-90/72