Subtract 21/8 from 21/84, Solve 21/84

Subtract 21/8 from 21/84

1^st number: 21/84, 2^nd number: 2 5/8

21/84 - 21/8 is -19/8.

Find the least common denominator or LCM of the two denominators:
LCM of 84 and 8 is 168

Next, find the equivalent fraction of both fractional numbers with denominator 168
For the 1st fraction, since 84 × 2 = 168,
21/84 = 21 × 2/84 × 2 = 42/168
Likewise, for the 2nd fraction, since 8 × 21 = 168,
21/8 = 21 × 21/8 × 21 = 441/168
Subtract the two like fractions:
42/168 - 441/168 = 42 - 441/168 = -399/168
After reducing the fraction, the answer is -19/8

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