Subtract 20/5 from 18/42
1st number: 18/42, 2nd number: 4 0/5
18/42 - 20/5 is -25/7.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 42 and 5 is 210
Next, find the equivalent fraction of both fractional numbers with denominator 210 - For the 1st fraction, since 42 × 5 = 210,
18/42 = 18 × 5/42 × 5 = 90/210 - Likewise, for the 2nd fraction, since 5 × 42 = 210,
20/5 = 20 × 42/5 × 42 = 840/210 - Subtract the two like fractions:
90/210 - 840/210 = 90 - 840/210 = -750/210 - After reducing the fraction, the answer is -25/7
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 36/42-20/5 18/42-40/5 18/84-20/5 18/42-20/10 54/42-20/5 18/42-60/5 18/42-20/15 90/42-20/5 18/42-20/25 18/42-20/35