Subtract 20/42 from 15/90
15/90 - 20/42 is -13/42.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 90 and 42 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 42 × 15 = 630,
20/42 = 20 × 15/42 × 15 = 300/630 - Subtract the two like fractions:
105/630 - 300/630 = 105 - 300/630 = -195/630 - After reducing the fraction, the answer is -13/42
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 30/90-20/42 15/90-40/42 15/90-20/84 45/90-20/42 15/90-60/42 75/90-20/42