Subtract 42/9 from 21/18
1st number: 1 3/18, 2nd number: 4 6/9
21/18 - 42/9 is -7/2.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 18 and 9 is 18
Next, find the equivalent fraction of both fractional numbers with denominator 18 - For the 1st fraction, since 18 × 1 = 18,
21/18 = 21 × 1/18 × 1 = 21/18 - Likewise, for the 2nd fraction, since 9 × 2 = 18,
42/9 = 42 × 2/9 × 2 = 84/18 - Subtract the two like fractions:
21/18 - 84/18 = 21 - 84/18 = -63/18 - After reducing the fraction, the answer is -7/2
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/18-42/9 21/18-84/9 21/36-42/9 21/18-42/18 63/18-42/9 21/54-42/9 21/18-42/27 21/90-42/9 21/18-42/45 21/18-42/63