Subtract 18/27 from 21/42
21/42 - 18/27 is -1/6.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 42 and 27 is 378
Next, find the equivalent fraction of both fractional numbers with denominator 378 - For the 1st fraction, since 42 × 9 = 378,
21/42 = 21 × 9/42 × 9 = 189/378 - Likewise, for the 2nd fraction, since 27 × 14 = 378,
18/27 = 18 × 14/27 × 14 = 252/378 - Subtract the two like fractions:
189/378 - 252/378 = 189 - 252/378 = -63/378 - After reducing the fraction, the answer is -1/6
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