Subtract 8/18 from 21/42
21/42 - 8/18 is 1/18.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 42 and 18 is 126
Next, find the equivalent fraction of both fractional numbers with denominator 126 - For the 1st fraction, since 42 × 3 = 126,
21/42 = 21 × 3/42 × 3 = 63/126 - Likewise, for the 2nd fraction, since 18 × 7 = 126,
8/18 = 8 × 7/18 × 7 = 56/126 - Subtract the two like fractions:
63/126 - 56/126 = 63 - 56/126 = 7/126 - After reducing the fraction, the answer is 1/18
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 21/42-16/18 21/84-8/18 21/42-8/36 63/42-8/18 21/42-24/18 21/42-8/54 21/42-40/18 21/42-8/90 21/42-56/18