Subtract 4/21 from 18/42
18/42 - 4/21 is 5/21.
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,
18/42 = 18 × 1/42 × 1 = 18/42 - Likewise, for the 2nd fraction, since 21 × 2 = 42,
4/21 = 4 × 2/21 × 2 = 8/42 - Subtract the two like fractions:
18/42 - 8/42 = 18 - 8/42 = 10/42 - After reducing the fraction, the answer is 5/21
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 36/42-4/21 18/42-8/21 18/84-4/21 18/42-4/42 54/42-4/21 18/42-12/21 18/42-4/63 90/42-4/21 18/42-20/21 18/42-28/21