Subtract 30/20 from 20/21
1st number: 20/21, 2nd number: 1 10/20
20/21 - 30/20 is -23/42.
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,
20/21 = 20 × 20/21 × 20 = 400/420 - Likewise, for the 2nd fraction, since 20 × 21 = 420,
30/20 = 30 × 21/20 × 21 = 630/420 - Subtract the two like fractions:
400/420 - 630/420 = 400 - 630/420 = -230/420 - After reducing the fraction, the answer is -23/42
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 40/21-30/20 20/21-60/20 20/42-30/20 20/21-30/40 60/21-30/20 20/21-90/20 20/63-30/20 20/21-30/60