Subtract 27/21 from 15/18
1st number: 15/18, 2nd number: 1 6/21
15/18 - 27/21 is -19/42.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 18 and 21 is 126
Next, find the equivalent fraction of both fractional numbers with denominator 126 - For the 1st fraction, since 18 × 7 = 126,
15/18 = 15 × 7/18 × 7 = 105/126 - Likewise, for the 2nd fraction, since 21 × 6 = 126,
27/21 = 27 × 6/21 × 6 = 162/126 - Subtract the two like fractions:
105/126 - 162/126 = 105 - 162/126 = -57/126 - After reducing the fraction, the answer is -19/42
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 30/18-27/21 15/18-54/21 15/36-27/21 15/18-27/42 45/18-27/21 15/18-81/21 15/54-27/21 15/18-27/63 75/18-27/21 15/90-27/21