Subtract 28/7 from 21/90
1st number: 21/90, 2nd number: 4 0/7
21/90 - 28/7 is -113/30.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 90 and 7 is 630
Next, find the equivalent fraction of both fractional numbers with denominator 630 - For the 1st fraction, since 90 × 7 = 630,
21/90 = 21 × 7/90 × 7 = 147/630 - Likewise, for the 2nd fraction, since 7 × 90 = 630,
28/7 = 28 × 90/7 × 90 = 2520/630 - Subtract the two like fractions:
147/630 - 2520/630 = 147 - 2520/630 = -2373/630 - After reducing the fraction, the answer is -113/30
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/90-28/7 21/90-56/7 21/90-28/14 63/90-28/7 21/90-84/7 21/90-28/21 21/90-28/35 21/90-28/49