Subtract 9/21 from 10/90
10/90 - 9/21 is -20/63.
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,
10/90 = 10 × 7/90 × 7 = 70/630 - Likewise, for the 2nd fraction, since 21 × 30 = 630,
9/21 = 9 × 30/21 × 30 = 270/630 - Subtract the two like fractions:
70/630 - 270/630 = 70 - 270/630 = -200/630 - After reducing the fraction, the answer is -20/63
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 20/90-9/21 10/90-18/21 10/90-9/42 30/90-9/21 10/90-27/21 10/90-9/63 50/90-9/21 10/90-45/21 70/90-9/21 10/90-63/21