Subtract 20/8 from 15/21
1st number: 15/21, 2nd number: 2 4/8
15/21 - 20/8 is -25/14.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 8 is 168
Next, find the equivalent fraction of both fractional numbers with denominator 168 - For the 1st fraction, since 21 × 8 = 168,
15/21 = 15 × 8/21 × 8 = 120/168 - Likewise, for the 2nd fraction, since 8 × 21 = 168,
20/8 = 20 × 21/8 × 21 = 420/168 - Subtract the two like fractions:
120/168 - 420/168 = 120 - 420/168 = -300/168 - After reducing the fraction, the answer is -25/14
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 30/21-20/8 15/21-40/8 15/42-20/8 15/21-20/16 45/21-20/8 15/21-60/8 15/63-20/8 15/21-20/24 75/21-20/8 15/21-20/40 15/21-20/56