Subtract 3/4 from 20/21
20/21 - 3/4 is 17/84.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 4 is 84
Next, find the equivalent fraction of both fractional numbers with denominator 84 - For the 1st fraction, since 21 × 4 = 84,
20/21 = 20 × 4/21 × 4 = 80/84 - Likewise, for the 2nd fraction, since 4 × 21 = 84,
3/4 = 3 × 21/4 × 21 = 63/84 - Subtract the two like fractions:
80/84 - 63/84 = 80 - 63/84 = 17/84
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 40/21-3/4 20/21-6/4 20/42-3/4 20/21-3/8 60/21-3/4 20/21-9/4 20/63-3/4 20/21-3/12 20/21-15/4 20/21-3/20 20/21-21/4 20/21-3/28