Subtract 72/90 from 30/21
1st number: 1 9/21, 2nd number: 72/90
30/21 - 72/90 is 22/35.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 90 is 630
Next, find the equivalent fraction of both fractional numbers with denominator 630 - For the 1st fraction, since 21 × 30 = 630,
30/21 = 30 × 30/21 × 30 = 900/630 - Likewise, for the 2nd fraction, since 90 × 7 = 630,
72/90 = 72 × 7/90 × 7 = 504/630 - Subtract the two like fractions:
900/630 - 504/630 = 900 - 504/630 = 396/630 - After reducing the fraction, the answer is 22/35
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 60/21-72/90 30/42-72/90 90/21-72/90 30/63-72/90