Subtract 1/5 from 20/21
20/21 - 1/5 is 79/105.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 5 is 105
Next, find the equivalent fraction of both fractional numbers with denominator 105 - For the 1st fraction, since 21 × 5 = 105,
20/21 = 20 × 5/21 × 5 = 100/105 - Likewise, for the 2nd fraction, since 5 × 21 = 105,
1/5 = 1 × 21/5 × 21 = 21/105 - Subtract the two like fractions:
100/105 - 21/105 = 100 - 21/105 = 79/105
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 40/21-1/5 20/21-2/5 20/42-1/5 20/21-1/10 60/21-1/5 20/21-3/5 20/63-1/5 20/21-1/15 20/21-1/25 20/21-7/5 20/21-1/35