Answers

Add 45/72 and 80/21

1^st number: 45/72, 2^nd number: 3 17/21

45/72 + 80/21 is 745/168.

Steps for adding fractions

1. Find the least common denominator or LCM of the two denominators:
   LCM of 72 and 21 is 504
   
   Next, find the equivalent fraction of both fractional numbers with denominator 504
2. For the 1st fraction, since 72 × 7 = 504,
   45/72 = 45 × 7/72 × 7 = 315/504
3. Likewise, for the 2nd fraction, since 21 × 24 = 504,
   80/21 = 80 × 24/21 × 24 = 1920/504
4. Add the two like fractions:
   315/504 + 1920/504 = 315 + 1920/504 = 2235/504
5. 2235/504 simplified gives 745/168
6. So, 45/72 + 80/21 = 745/168
   In mixed form: 473/168

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