Subtract 15/30 from 8/21
8/21 - 15/30 is -5/42.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 30 is 210
Next, find the equivalent fraction of both fractional numbers with denominator 210 - For the 1st fraction, since 21 × 10 = 210,
8/21 = 8 × 10/21 × 10 = 80/210 - Likewise, for the 2nd fraction, since 30 × 7 = 210,
15/30 = 15 × 7/30 × 7 = 105/210 - Subtract the two like fractions:
80/210 - 105/210 = 80 - 105/210 = -25/210 - After reducing the fraction, the answer is -5/42
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 16/21-15/30 8/42-15/30 8/21-15/60 24/21-15/30 8/21-45/30 8/63-15/30 8/21-15/90 40/21-15/30 8/21-75/30 56/21-15/30