Subtract 8/5 from 18/21
1st number: 18/21, 2nd number: 1 3/5
18/21 - 8/5 is -26/35.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 5 is 105
Next, find the equivalent fraction of both fractional numbers with denominator 105 - For the 1st fraction, since 21 × 5 = 105,
18/21 = 18 × 5/21 × 5 = 90/105 - Likewise, for the 2nd fraction, since 5 × 21 = 105,
8/5 = 8 × 21/5 × 21 = 168/105 - Subtract the two like fractions:
90/105 - 168/105 = 90 - 168/105 = -78/105 - After reducing the fraction, the answer is -26/35
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 36/21-8/5 18/21-16/5 18/42-8/5 18/21-8/10 54/21-8/5 18/21-24/5 18/63-8/5 18/21-8/15 90/21-8/5 18/21-40/5 18/21-8/25 18/21-56/5 18/21-8/35