Subtract 9/21 from 9/90
9/90 - 9/21 is -23/70.
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,
9/90 = 9 × 7/90 × 7 = 63/630 - Likewise, for the 2nd fraction, since 21 × 30 = 630,
9/21 = 9 × 30/21 × 30 = 270/630 - Subtract the two like fractions:
63/630 - 270/630 = 63 - 270/630 = -207/630 - After reducing the fraction, the answer is -23/70
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 18/90-9/21 9/90-18/21 9/90-9/42 27/90-9/21 9/90-27/21 9/90-9/63 45/90-9/21 9/90-45/21 63/90-9/21 9/90-63/21