Subtract 6/18 from 20/21
20/21 - 6/18 is 13/21.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 18 is 126
Next, find the equivalent fraction of both fractional numbers with denominator 126 - For the 1st fraction, since 21 × 6 = 126,
20/21 = 20 × 6/21 × 6 = 120/126 - Likewise, for the 2nd fraction, since 18 × 7 = 126,
6/18 = 6 × 7/18 × 7 = 42/126 - Subtract the two like fractions:
120/126 - 42/126 = 120 - 42/126 = 78/126 - After reducing the fraction, the answer is 13/21
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 40/21-6/18 20/21-12/18 20/42-6/18 20/21-6/36 60/21-6/18 20/63-6/18 20/21-6/54 20/21-30/18 20/21-6/90 20/21-42/18