Subtract 10/90 from 42/21
1st number: 2 0/21, 2nd number: 10/90
42/21 - 10/90 is 17/9.
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,
42/21 = 42 × 30/21 × 30 = 1260/630 - Likewise, for the 2nd fraction, since 90 × 7 = 630,
10/90 = 10 × 7/90 × 7 = 70/630 - Subtract the two like fractions:
1260/630 - 70/630 = 1260 - 70/630 = 1190/630 - After reducing the fraction, the answer is 17/9
- In mixed form: 18/9
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 84/21-10/90 42/21-20/90 42/21-30/90 42/63-10/90 42/21-50/90 42/21-70/90