Subtract 5/21 from 15/90
15/90 - 5/21 is -1/14.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 90 and 21 is 630
Next, find the equivalent fraction of both fractional numbers with denominator 630 - For the 1st fraction, since 90 × 7 = 630,
15/90 = 15 × 7/90 × 7 = 105/630 - Likewise, for the 2nd fraction, since 21 × 30 = 630,
5/21 = 5 × 30/21 × 30 = 150/630 - Subtract the two like fractions:
105/630 - 150/630 = 105 - 150/630 = -45/630 - After reducing the fraction, the answer is -1/14
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 30/90-5/21 15/90-10/21 15/90-5/42 45/90-5/21 15/90-15/21 15/90-5/63 75/90-5/21 15/90-25/21 15/90-35/21