Subtract 75/90 from 20/21
20/21 - 75/90 is 5/42.
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,
20/21 = 20 × 30/21 × 30 = 600/630 - Likewise, for the 2nd fraction, since 90 × 7 = 630,
75/90 = 75 × 7/90 × 7 = 525/630 - Subtract the two like fractions:
600/630 - 525/630 = 600 - 525/630 = 75/630 - 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: 40/21-75/90 20/42-75/90 60/21-75/90 20/63-75/90