Subtract 21/20 from 12/42
1st number: 12/42, 2nd number: 1 1/20
12/42 - 21/20 is -107/140.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 42 and 20 is 420
Next, find the equivalent fraction of both fractional numbers with denominator 420 - For the 1st fraction, since 42 × 10 = 420,
12/42 = 12 × 10/42 × 10 = 120/420 - Likewise, for the 2nd fraction, since 20 × 21 = 420,
21/20 = 21 × 21/20 × 21 = 441/420 - Subtract the two like fractions:
120/420 - 441/420 = 120 - 441/420 = -321/420 - After reducing the fraction, the answer is -107/140
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 24/42-21/20 12/42-42/20 12/84-21/20 12/42-21/40 36/42-21/20 12/42-63/20 12/42-21/60 60/42-21/20 84/42-21/20