Subtract 81/18 from 20/5
1st number: 4 0/5, 2nd number: 4 9/18
20/5 - 81/18 is -1/2.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 5 and 18 is 90
Next, find the equivalent fraction of both fractional numbers with denominator 90 - For the 1st fraction, since 5 × 18 = 90,
20/5 = 20 × 18/5 × 18 = 360/90 - Likewise, for the 2nd fraction, since 18 × 5 = 90,
81/18 = 81 × 5/18 × 5 = 405/90 - Subtract the two like fractions:
360/90 - 405/90 = 360 - 405/90 = -45/90 - 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: 40/5-81/18 20/10-81/18 20/5-81/36 60/5-81/18 20/15-81/18 20/5-81/54 20/25-81/18 20/5-81/90 20/35-81/18