Subtract 42/56 from 20/21
20/21 - 42/56 is 17/84.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 56 is 168
Next, find the equivalent fraction of both fractional numbers with denominator 168 - For the 1st fraction, since 21 × 8 = 168,
20/21 = 20 × 8/21 × 8 = 160/168 - Likewise, for the 2nd fraction, since 56 × 3 = 168,
42/56 = 42 × 3/56 × 3 = 126/168 - Subtract the two like fractions:
160/168 - 126/168 = 160 - 126/168 = 34/168 - After reducing the fraction, the answer is 17/84
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