Subtract 15/18 from 20/84, Solve 20/84

Subtract 15/18 from 20/84

20/84 - 15/18 is -25/42.

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,
15/18 = 15 × 14/18 × 14 = 210/252
Subtract the two like fractions:
60/252 - 210/252 = 60 - 210/252 = -150/252
After reducing the fraction, the answer is -25/42

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