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