Subtract 15/90 from 4/21
4/21 - 15/90 is 1/42.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 90 is 630
Next, find the equivalent fraction of both fractional numbers with denominator 630 - For the 1st fraction, since 21 × 30 = 630,
4/21 = 4 × 30/21 × 30 = 120/630 - Likewise, for the 2nd fraction, since 90 × 7 = 630,
15/90 = 15 × 7/90 × 7 = 105/630 - Subtract the two like fractions:
120/630 - 105/630 = 120 - 105/630 = 15/630 - After reducing the fraction, the answer is 1/42
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 8/21-15/90 4/21-30/90 4/42-15/90 12/21-15/90 4/21-45/90 4/63-15/90 20/21-15/90 4/21-75/90 28/21-15/90