Subtract 42/21 from 12/20
1st number: 12/20, 2nd number: 2 0/21
12/20 - 42/21 is -7/5.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 20 and 21 is 420
Next, find the equivalent fraction of both fractional numbers with denominator 420 - For the 1st fraction, since 20 × 21 = 420,
12/20 = 12 × 21/20 × 21 = 252/420 - Likewise, for the 2nd fraction, since 21 × 20 = 420,
42/21 = 42 × 20/21 × 20 = 840/420 - Subtract the two like fractions:
252/420 - 840/420 = 252 - 840/420 = -588/420 - After reducing the fraction, the answer is -7/5
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 24/20-42/21 12/20-84/21 12/40-42/21 36/20-42/21 12/60-42/21 12/20-42/63 60/20-42/21 84/20-42/21