Answers

Add 12/81 and 9/21

12/81 + 9/21 is 109/189.

Steps for adding fractions

1. Find the least common denominator or LCM of the two denominators:
   LCM of 81 and 21 is 567
   
   Next, find the equivalent fraction of both fractional numbers with denominator 567
2. For the 1st fraction, since 81 × 7 = 567,
   12/81 = 12 × 7/81 × 7 = 84/567
3. Likewise, for the 2nd fraction, since 21 × 27 = 567,
   9/21 = 9 × 27/21 × 27 = 243/567
4. Add the two like fractions:
   84/567 + 243/567 = 84 + 243/567 = 327/567
5. 327/567 simplified gives 109/189
6. So, 12/81 + 9/21 = 109/189

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