Subtract 15/45 from 20/42
20/42 - 15/45 is 1/7.
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,
15/45 = 15 × 14/45 × 14 = 210/630 - Subtract the two like fractions:
300/630 - 210/630 = 300 - 210/630 = 90/630 - After reducing the fraction, the answer is 1/7
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 40/42-15/45 20/42-30/45 20/84-15/45 20/42-15/90 60/42-15/45 20/42-75/45