Answers

Add 72/81 and 45/20

1^st number: 72/81, 2^nd number: 2 5/20

72/81 + 45/20 is 113/36.

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,
   72/81 = 72 × 20/81 × 20 = 1440/1620
3. Likewise, for the 2nd fraction, since 20 × 81 = 1620,
   45/20 = 45 × 81/20 × 81 = 3645/1620
4. Add the two like fractions:
   1440/1620 + 3645/1620 = 1440 + 3645/1620 = 5085/1620
5. 5085/1620 simplified gives 113/36
6. So, 72/81 + 45/20 = 113/36
   In mixed form: 35/36

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