Answers

Add 81/72 and 20/42

1^st number: 1 9/72, 2^nd number: 20/42

81/72 + 20/42 is 269/168.

Steps for adding fractions

1. Find the least common denominator or LCM of the two denominators:
   LCM of 72 and 42 is 504
   
   Next, find the equivalent fraction of both fractional numbers with denominator 504
2. For the 1st fraction, since 72 × 7 = 504,
   81/72 = 81 × 7/72 × 7 = 567/504
3. Likewise, for the 2nd fraction, since 42 × 12 = 504,
   20/42 = 20 × 12/42 × 12 = 240/504
4. Add the two like fractions:
   567/504 + 240/504 = 567 + 240/504 = 807/504
5. 807/504 simplified gives 269/168
6. So, 81/72 + 20/42 = 269/168
   In mixed form: 1101/168

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