Subtract 40/42 from 9/21
9/21 - 40/42 is -11/21.
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,
9/21 = 9 × 2/21 × 2 = 18/42 - Likewise, for the 2nd fraction, since 42 × 1 = 42,
40/42 = 40 × 1/42 × 1 = 40/42 - Subtract the two like fractions:
18/42 - 40/42 = 18 - 40/42 = -22/42 - After reducing the fraction, the answer is -11/21
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 18/21-40/42 9/21-80/42 9/42-40/42 9/21-40/84 27/21-40/42 9/63-40/42 45/21-40/42 63/21-40/42