Subtract 15/20 from 42/84
42/84 - 15/20 is -1/4.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 84 and 20 is 420
Next, find the equivalent fraction of both fractional numbers with denominator 420 - For the 1st fraction, since 84 × 5 = 420,
42/84 = 42 × 5/84 × 5 = 210/420 - Likewise, for the 2nd fraction, since 20 × 21 = 420,
15/20 = 15 × 21/20 × 21 = 315/420 - Subtract the two like fractions:
210/420 - 315/420 = 210 - 315/420 = -105/420 - After reducing the fraction, the answer is -1/4
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