Subtract 30/42 from 18/27
18/27 - 30/42 is -1/21.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 27 and 42 is 378
Next, find the equivalent fraction of both fractional numbers with denominator 378 - For the 1st fraction, since 27 × 14 = 378,
18/27 = 18 × 14/27 × 14 = 252/378 - Likewise, for the 2nd fraction, since 42 × 9 = 378,
30/42 = 30 × 9/42 × 9 = 270/378 - Subtract the two like fractions:
252/378 - 270/378 = 252 - 270/378 = -18/378 - After reducing the fraction, the answer is -1/21
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 36/27-30/42 18/27-60/42 18/54-30/42 18/27-30/84 54/27-30/42 18/27-90/42 18/81-30/42 90/27-30/42