Subtract 5/18 from 3/21
3/21 - 5/18 is -17/126.
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,
3/21 = 3 × 6/21 × 6 = 18/126 - Likewise, for the 2nd fraction, since 18 × 7 = 126,
5/18 = 5 × 7/18 × 7 = 35/126 - Subtract the two like fractions:
18/126 - 35/126 = 18 - 35/126 = -17/126
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 6/21-5/18 3/21-10/18 3/42-5/18 3/21-5/36 9/21-5/18 3/21-15/18 3/63-5/18 3/21-5/54 15/21-5/18 3/21-25/18 3/21-5/90 3/21-35/18