Subtract 50/21 from 81/90
1st number: 81/90, 2nd number: 2 8/21
81/90 - 50/21 is -311/210.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 90 and 21 is 630
Next, find the equivalent fraction of both fractional numbers with denominator 630 - For the 1st fraction, since 90 × 7 = 630,
81/90 = 81 × 7/90 × 7 = 567/630 - Likewise, for the 2nd fraction, since 21 × 30 = 630,
50/21 = 50 × 30/21 × 30 = 1500/630 - Subtract the two like fractions:
567/630 - 1500/630 = 567 - 1500/630 = -933/630 - After reducing the fraction, the answer is -311/210
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 81/90-50/42 81/90-50/63