Subtract 9/21 from 8/42
8/42 - 9/21 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,
8/42 = 8 × 1/42 × 1 = 8/42 - Likewise, for the 2nd fraction, since 21 × 2 = 42,
9/21 = 9 × 2/21 × 2 = 18/42 - Subtract the two like fractions:
8/42 - 18/42 = 8 - 18/42 = -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: 16/42-9/21 8/42-18/21 8/84-9/21 8/42-9/42 24/42-9/21 8/42-27/21 8/42-9/63 40/42-9/21 8/42-45/21 56/42-9/21 8/42-63/21