Subtract 3/7 from 12/21
12/21 - 3/7 is 1/7.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 7 is 21
Next, find the equivalent fraction of both fractional numbers with denominator 21 - For the 1st fraction, since 21 × 1 = 21,
12/21 = 12 × 1/21 × 1 = 12/21 - Likewise, for the 2nd fraction, since 7 × 3 = 21,
3/7 = 3 × 3/7 × 3 = 9/21 - Subtract the two like fractions:
12/21 - 9/21 = 12 - 9/21 = 3/21 - After reducing the fraction, the answer is 1/7
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 24/21-3/7 12/21-6/7 12/42-3/7 12/21-3/14 36/21-3/7 12/21-9/7 12/63-3/7 12/21-3/21 60/21-3/7 12/21-15/7 12/21-3/35 84/21-3/7 12/21-21/7 12/21-3/49