Subtract 21/8 from 15/18
1st number: 15/18, 2nd number: 2 5/8
15/18 - 21/8 is -43/24.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 18 and 8 is 72
Next, find the equivalent fraction of both fractional numbers with denominator 72 - For the 1st fraction, since 18 × 4 = 72,
15/18 = 15 × 4/18 × 4 = 60/72 - Likewise, for the 2nd fraction, since 8 × 9 = 72,
21/8 = 21 × 9/8 × 9 = 189/72 - Subtract the two like fractions:
60/72 - 189/72 = 60 - 189/72 = -129/72 - After reducing the fraction, the answer is -43/24
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 30/18-21/8 15/18-42/8 15/36-21/8 15/18-21/16 45/18-21/8 15/18-63/8 15/54-21/8 15/18-21/24 75/18-21/8 15/90-21/8 15/18-21/40 15/18-21/56