Subtract 16/5 from 21/84, Solve 21/84

Subtract 16/5 from 21/84

1^st number: 21/84, 2^nd number: 3 1/5

21/84 - 16/5 is -59/20.

Find the least common denominator or LCM of the two denominators:
LCM of 84 and 5 is 420

Next, find the equivalent fraction of both fractional numbers with denominator 420
For the 1st fraction, since 84 × 5 = 420,
21/84 = 21 × 5/84 × 5 = 105/420
Likewise, for the 2nd fraction, since 5 × 84 = 420,
16/5 = 16 × 84/5 × 84 = 1344/420
Subtract the two like fractions:
105/420 - 1344/420 = 105 - 1344/420 = -1239/420
After reducing the fraction, the answer is -59/20

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