Subtract 42/21 from 45/18
1st number: 2 9/18, 2nd number: 2 0/21
45/18 - 42/21 is 1/2.
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,
45/18 = 45 × 7/18 × 7 = 315/126 - Likewise, for the 2nd fraction, since 21 × 6 = 126,
42/21 = 42 × 6/21 × 6 = 252/126 - Subtract the two like fractions:
315/126 - 252/126 = 315 - 252/126 = 63/126 - After reducing the fraction, the answer is 1/2
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 90/18-42/21 45/18-84/21 45/36-42/21 45/54-42/21 45/18-42/63 45/90-42/21