Subtract 84/90 from 5/21
5/21 - 84/90 is -73/105.
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,
5/21 = 5 × 30/21 × 30 = 150/630 - Likewise, for the 2nd fraction, since 90 × 7 = 630,
84/90 = 84 × 7/90 × 7 = 588/630 - Subtract the two like fractions:
150/630 - 588/630 = 150 - 588/630 = -438/630 - After reducing the fraction, the answer is -73/105
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 10/21-84/90 5/42-84/90 15/21-84/90 5/63-84/90 25/21-84/90 35/21-84/90