Subtract 21/90 from 9/70
9/70 - 21/90 is -11/105.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 70 and 90 is 630
Next, find the equivalent fraction of both fractional numbers with denominator 630 - For the 1st fraction, since 70 × 9 = 630,
9/70 = 9 × 9/70 × 9 = 81/630 - Likewise, for the 2nd fraction, since 90 × 7 = 630,
21/90 = 21 × 7/90 × 7 = 147/630 - Subtract the two like fractions:
81/630 - 147/630 = 81 - 147/630 = -66/630 - After reducing the fraction, the answer is -11/105
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 18/70-21/90 9/70-42/90 27/70-21/90 9/70-63/90 45/70-21/90 63/70-21/90