Subtract 21/5 from 42/18
1st number: 2 6/18, 2nd number: 4 1/5
42/18 - 21/5 is -28/15.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 18 and 5 is 90
Next, find the equivalent fraction of both fractional numbers with denominator 90 - For the 1st fraction, since 18 × 5 = 90,
42/18 = 42 × 5/18 × 5 = 210/90 - Likewise, for the 2nd fraction, since 5 × 18 = 90,
21/5 = 21 × 18/5 × 18 = 378/90 - Subtract the two like fractions:
210/90 - 378/90 = 210 - 378/90 = -168/90 - After reducing the fraction, the answer is -28/15
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 84/18-21/5 42/18-42/5 42/36-21/5 42/18-21/10 42/18-63/5 42/54-21/5 42/18-21/15 42/90-21/5 42/18-21/25 42/18-21/35