Subtract 8/21 from 9/20
9/20 - 8/21 is 29/420.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 20 and 21 is 420
Next, find the equivalent fraction of both fractional numbers with denominator 420 - For the 1st fraction, since 20 × 21 = 420,
9/20 = 9 × 21/20 × 21 = 189/420 - Likewise, for the 2nd fraction, since 21 × 20 = 420,
8/21 = 8 × 20/21 × 20 = 160/420 - Subtract the two like fractions:
189/420 - 160/420 = 189 - 160/420 = 29/420
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 18/20-8/21 9/20-16/21 9/40-8/21 9/20-8/42 27/20-8/21 9/20-24/21 9/60-8/21 9/20-8/63 45/20-8/21 9/20-40/21 63/20-8/21 9/20-56/21