Subtract 4/42 from 8/21
8/21 - 4/42 is 2/7.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 42 is 42
Next, find the equivalent fraction of both fractional numbers with denominator 42 - For the 1st fraction, since 21 × 2 = 42,
8/21 = 8 × 2/21 × 2 = 16/42 - Likewise, for the 2nd fraction, since 42 × 1 = 42,
4/42 = 4 × 1/42 × 1 = 4/42 - Subtract the two like fractions:
16/42 - 4/42 = 16 - 4/42 = 12/42 - After reducing the fraction, the answer is 2/7
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 16/21-4/42 8/21-8/42 8/42-4/42 8/21-4/84 24/21-4/42 8/21-12/42 8/63-4/42 40/21-4/42 8/21-20/42 56/21-4/42 8/21-28/42