Subtract 20/12 from 3/21
1st number: 3/21, 2nd number: 1 8/12
3/21 - 20/12 is -32/21.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 12 is 84
Next, find the equivalent fraction of both fractional numbers with denominator 84 - For the 1st fraction, since 21 × 4 = 84,
3/21 = 3 × 4/21 × 4 = 12/84 - Likewise, for the 2nd fraction, since 12 × 7 = 84,
20/12 = 20 × 7/12 × 7 = 140/84 - Subtract the two like fractions:
12/84 - 140/84 = 12 - 140/84 = -128/84 - After reducing the fraction, the answer is -32/21
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 6/21-20/12 3/21-40/12 3/42-20/12 3/21-20/24 9/21-20/12 3/21-60/12 3/63-20/12 3/21-20/36 15/21-20/12 3/21-20/60 3/21-20/84