Subtract 15/81 from 1/21, Solve 1/21

Subtract 15/81 from 1/21

1/21 - 15/81 is -26/189.

Find the least common denominator or LCM of the two denominators:
LCM of 21 and 81 is 567

Next, find the equivalent fraction of both fractional numbers with denominator 567
For the 1st fraction, since 21 × 27 = 567,
1/21 = 1 × 27/21 × 27 = 27/567
Likewise, for the 2nd fraction, since 81 × 7 = 567,
15/81 = 15 × 7/81 × 7 = 105/567
Subtract the two like fractions:
27/567 - 105/567 = 27 - 105/567 = -78/567
After reducing the fraction, the answer is -26/189

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