Subtract 4/20 from 81/21
1st number: 3 18/21, 2nd number: 4/20
81/21 - 4/20 is 128/35.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 20 is 420
Next, find the equivalent fraction of both fractional numbers with denominator 420 - For the 1st fraction, since 21 × 20 = 420,
81/21 = 81 × 20/21 × 20 = 1620/420 - Likewise, for the 2nd fraction, since 20 × 21 = 420,
4/20 = 4 × 21/20 × 21 = 84/420 - Subtract the two like fractions:
1620/420 - 84/420 = 1620 - 84/420 = 1536/420 - After reducing the fraction, the answer is 128/35
- In mixed form: 323/35
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 81/21-8/20 81/42-4/20 81/21-4/40 81/21-12/20 81/63-4/20 81/21-4/60 81/21-28/20