Subtract 15/18 from 18/21
18/21 - 15/18 is 1/42.
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,
18/21 = 18 × 6/21 × 6 = 108/126 - Likewise, for the 2nd fraction, since 18 × 7 = 126,
15/18 = 15 × 7/18 × 7 = 105/126 - Subtract the two like fractions:
108/126 - 105/126 = 108 - 105/126 = 3/126 - After reducing the fraction, the answer is 1/42
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 36/21-15/18 18/21-30/18 18/42-15/18 18/21-15/36 54/21-15/18 18/21-45/18 18/63-15/18 18/21-15/54 90/21-15/18 18/21-75/18 18/21-15/90