Subtract 20/81 from 7/42
7/42 - 20/81 is -13/162.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 42 and 81 is 1134
Next, find the equivalent fraction of both fractional numbers with denominator 1134 - For the 1st fraction, since 42 × 27 = 1134,
7/42 = 7 × 27/42 × 27 = 189/1134 - Likewise, for the 2nd fraction, since 81 × 14 = 1134,
20/81 = 20 × 14/81 × 14 = 280/1134 - Subtract the two like fractions:
189/1134 - 280/1134 = 189 - 280/1134 = -91/1134 - After reducing the fraction, the answer is -13/162
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 14/42-20/81 7/42-40/81 7/84-20/81 21/42-20/81 7/42-60/81 35/42-20/81 49/42-20/81