Subtract 20/21 from 9/10
9/10 - 20/21 is -11/210.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 10 and 21 is 210
Next, find the equivalent fraction of both fractional numbers with denominator 210 - For the 1st fraction, since 10 × 21 = 210,
9/10 = 9 × 21/10 × 21 = 189/210 - Likewise, for the 2nd fraction, since 21 × 10 = 210,
20/21 = 20 × 10/21 × 10 = 200/210 - Subtract the two like fractions:
189/210 - 200/210 = 189 - 200/210 = -11/210
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 18/10-20/21 9/10-40/21 9/20-20/21 9/10-20/42 27/10-20/21 9/10-60/21 9/30-20/21 9/10-20/63 45/10-20/21 9/50-20/21 63/10-20/21 9/70-20/21