Answers

Add 20/81 and 21/84

20/81 + 21/84 is 161/324.

Steps for adding fractions

1. Find the least common denominator or LCM of the two denominators:
   LCM of 81 and 84 is 2268
   
   Next, find the equivalent fraction of both fractional numbers with denominator 2268
2. For the 1st fraction, since 81 × 28 = 2268,
   20/81 = 20 × 28/81 × 28 = 560/2268
3. Likewise, for the 2nd fraction, since 84 × 27 = 2268,
   21/84 = 21 × 27/84 × 27 = 567/2268
4. Add the two like fractions:
   560/2268 + 567/2268 = 560 + 567/2268 = 1127/2268
5. 1127/2268 simplified gives 161/324
6. So, 20/81 + 21/84 = 161/324

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