Answers

Add 72/21 and 45/81

1^st number: 3 9/21, 2^nd number: 45/81

72/21 + 45/81 is 251/63.

Steps for adding fractions

1. 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
2. For the 1st fraction, since 21 × 27 = 567,
   72/21 = 72 × 27/21 × 27 = 1944/567
3. Likewise, for the 2nd fraction, since 81 × 7 = 567,
   45/81 = 45 × 7/81 × 7 = 315/567
4. Add the two like fractions:
   1944/567 + 315/567 = 1944 + 315/567 = 2259/567
5. 2259/567 simplified gives 251/63
6. So, 72/21 + 45/81 = 251/63
   In mixed form: 362/63

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