Subtract 15/21 from 8/18
8/18 - 15/21 is -17/63.
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,
8/18 = 8 × 7/18 × 7 = 56/126 - Likewise, for the 2nd fraction, since 21 × 6 = 126,
15/21 = 15 × 6/21 × 6 = 90/126 - Subtract the two like fractions:
56/126 - 90/126 = 56 - 90/126 = -34/126 - After reducing the fraction, the answer is -17/63
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 16/18-15/21 8/18-30/21 8/36-15/21 8/18-15/42 24/18-15/21 8/18-45/21 8/54-15/21 8/18-15/63 40/18-15/21 8/18-75/21 8/90-15/21 56/18-15/21