Answers

Add 21/81 and 75/20

1^st number: 21/81, 2^nd number: 3 15/20

21/81 + 75/20 is 433/108.

Steps for adding fractions

1. Find the least common denominator or LCM of the two denominators:
   LCM of 81 and 20 is 1620
   
   Next, find the equivalent fraction of both fractional numbers with denominator 1620
2. For the 1st fraction, since 81 × 20 = 1620,
   21/81 = 21 × 20/81 × 20 = 420/1620
3. Likewise, for the 2nd fraction, since 20 × 81 = 1620,
   75/20 = 75 × 81/20 × 81 = 6075/1620
4. Add the two like fractions:
   420/1620 + 6075/1620 = 420 + 6075/1620 = 6495/1620
5. 6495/1620 simplified gives 433/108
6. So, 21/81 + 75/20 = 433/108
   In mixed form: 41/108

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