Subtract 84/21 from 20/42
1st number: 20/42, 2nd number: 4 0/21
20/42 - 84/21 is -74/21.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 42 and 21 is 42
Next, find the equivalent fraction of both fractional numbers with denominator 42 - For the 1st fraction, since 42 × 1 = 42,
20/42 = 20 × 1/42 × 1 = 20/42 - Likewise, for the 2nd fraction, since 21 × 2 = 42,
84/21 = 84 × 2/21 × 2 = 168/42 - Subtract the two like fractions:
20/42 - 168/42 = 20 - 168/42 = -148/42 - After reducing the fraction, the answer is -74/21
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 40/42-84/21 20/84-84/21 20/42-84/42 60/42-84/21 20/42-84/63