Subtract 81/49 from 21/84, Solve 21/84

Subtract 81/49 from 21/84

1^st number: 21/84, 2^nd number: 1 32/49

21/84 - 81/49 is -275/196.

Find the least common denominator or LCM of the two denominators:
LCM of 84 and 49 is 588

Next, find the equivalent fraction of both fractional numbers with denominator 588
For the 1st fraction, since 84 × 7 = 588,
21/84 = 21 × 7/84 × 7 = 147/588
Likewise, for the 2nd fraction, since 49 × 12 = 588,
81/49 = 81 × 12/49 × 12 = 972/588
Subtract the two like fractions:
147/588 - 972/588 = 147 - 972/588 = -825/588
After reducing the fraction, the answer is -275/196

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