Answers

Add 21/7 and 45/80

1^st number: 3 0/7, 2^nd number: 45/80

21/7 + 45/80 is 57/16.

Steps for adding fractions

1. Find the least common denominator or LCM of the two denominators:
   LCM of 7 and 80 is 560
   
   Next, find the equivalent fraction of both fractional numbers with denominator 560
2. For the 1st fraction, since 7 × 80 = 560,
   21/7 = 21 × 80/7 × 80 = 1680/560
3. Likewise, for the 2nd fraction, since 80 × 7 = 560,
   45/80 = 45 × 7/80 × 7 = 315/560
4. Add the two like fractions:
   1680/560 + 315/560 = 1680 + 315/560 = 1995/560
5. 1995/560 simplified gives 57/16
6. So, 21/7 + 45/80 = 57/16
   In mixed form: 39/16

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