Subtract 21/18 from 20/84, Solve 20/84

Subtract 21/18 from 20/84

1^st number: 20/84, 2^nd number: 1 3/18

20/84 - 21/18 is -13/14.

Find the least common denominator or LCM of the two denominators:
LCM of 84 and 18 is 252

Next, find the equivalent fraction of both fractional numbers with denominator 252
For the 1st fraction, since 84 × 3 = 252,
20/84 = 20 × 3/84 × 3 = 60/252
Likewise, for the 2nd fraction, since 18 × 14 = 252,
21/18 = 21 × 14/18 × 14 = 294/252
Subtract the two like fractions:
60/252 - 294/252 = 60 - 294/252 = -234/252
After reducing the fraction, the answer is -13/14

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