Subtract 84/18 from 3/21, Solve 3/21

Subtract 84/18 from 3/21

1^st number: 3/21, 2^nd number: 4 12/18

3/21 - 84/18 is -95/21.

Find the least common denominator or LCM of the two denominators:
LCM of 21 and 18 is 126

Next, find the equivalent fraction of both fractional numbers with denominator 126
For the 1st fraction, since 21 × 6 = 126,
3/21 = 3 × 6/21 × 6 = 18/126
Likewise, for the 2nd fraction, since 18 × 7 = 126,
84/18 = 84 × 7/18 × 7 = 588/126
Subtract the two like fractions:
18/126 - 588/126 = 18 - 588/126 = -570/126
After reducing the fraction, the answer is -95/21

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