Subtract 5/21 from 42/84
42/84 - 5/21 is 11/42.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 84 and 21 is 84
Next, find the equivalent fraction of both fractional numbers with denominator 84 - For the 1st fraction, since 84 × 1 = 84,
42/84 = 42 × 1/84 × 1 = 42/84 - Likewise, for the 2nd fraction, since 21 × 4 = 84,
5/21 = 5 × 4/21 × 4 = 20/84 - Subtract the two like fractions:
42/84 - 20/84 = 42 - 20/84 = 22/84 - After reducing the fraction, the answer is 11/42
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/84-10/21 42/84-5/42 42/84-15/21 42/84-5/63 42/84-25/21 42/84-35/21