Subtract 20/12 from 12/42
1st number: 12/42, 2nd number: 1 8/12
12/42 - 20/12 is -29/21.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 42 and 12 is 84
Next, find the equivalent fraction of both fractional numbers with denominator 84 - For the 1st fraction, since 42 × 2 = 84,
12/42 = 12 × 2/42 × 2 = 24/84 - Likewise, for the 2nd fraction, since 12 × 7 = 84,
20/12 = 20 × 7/12 × 7 = 140/84 - Subtract the two like fractions:
24/84 - 140/84 = 24 - 140/84 = -116/84 - After reducing the fraction, the answer is -29/21
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 24/42-20/12 12/42-40/12 12/84-20/12 12/42-20/24 36/42-20/12 12/42-60/12 12/42-20/36 60/42-20/12 12/42-20/60 84/42-20/12 12/42-20/84