Subtract 90/45 from 20/42
1st number: 20/42, 2nd number: 2 0/45
20/42 - 90/45 is -32/21.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 42 and 45 is 630
Next, find the equivalent fraction of both fractional numbers with denominator 630 - For the 1st fraction, since 42 × 15 = 630,
20/42 = 20 × 15/42 × 15 = 300/630 - Likewise, for the 2nd fraction, since 45 × 14 = 630,
90/45 = 90 × 14/45 × 14 = 1260/630 - Subtract the two like fractions:
300/630 - 1260/630 = 300 - 1260/630 = -960/630 - After reducing the fraction, the answer is -32/21
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 40/42-90/45 20/84-90/45 60/42-90/45