Subtract 7/18 from 7/21
7/21 - 7/18 is -1/18.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 18 is 126
Next, find the equivalent fraction of both fractional numbers with denominator 126 - For the 1st fraction, since 21 × 6 = 126,
7/21 = 7 × 6/21 × 6 = 42/126 - Likewise, for the 2nd fraction, since 18 × 7 = 126,
7/18 = 7 × 7/18 × 7 = 49/126 - Subtract the two like fractions:
42/126 - 49/126 = 42 - 49/126 = -7/126 - After reducing the fraction, the answer is -1/18
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 14/21-7/18 7/21-14/18 7/42-7/18 7/21-7/36 7/21-21/18 7/63-7/18 7/21-7/54 35/21-7/18 7/21-35/18 7/21-7/90 49/21-7/18 7/21-49/18