Answers

Add 80/21 and 40/72

1^st number: 3 17/21, 2^nd number: 40/72

80/21 + 40/72 is 275/63.

Steps for adding fractions

1. Find the least common denominator or LCM of the two denominators:
   LCM of 21 and 72 is 504
   
   Next, find the equivalent fraction of both fractional numbers with denominator 504
2. For the 1st fraction, since 21 × 24 = 504,
   80/21 = 80 × 24/21 × 24 = 1920/504
3. Likewise, for the 2nd fraction, since 72 × 7 = 504,
   40/72 = 40 × 7/72 × 7 = 280/504
4. Add the two like fractions:
   1920/504 + 280/504 = 1920 + 280/504 = 2200/504
5. 2200/504 simplified gives 275/63
6. So, 80/21 + 40/72 = 275/63
   In mixed form: 423/63

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