Subtract 18/84 from 7/42
7/42 - 18/84 is -1/21.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 42 and 84 is 84
Next, find the equivalent fraction of both fractional numbers with denominator 84 - For the 1st fraction, since 42 × 2 = 84,
7/42 = 7 × 2/42 × 2 = 14/84 - Likewise, for the 2nd fraction, since 84 × 1 = 84,
18/84 = 18 × 1/84 × 1 = 18/84 - Subtract the two like fractions:
14/84 - 18/84 = 14 - 18/84 = -4/84 - After reducing the fraction, the answer is -1/21
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