Plz with 13,15,the 3 pizza problem and 12 chicken problem. for the 3 pizza and chicken u round ur answer to nearest hundreth .aka have to do unit rate and better buy means cheaper price.7 point

13)  So essentially what your finding is how much you're paying per penguin in each case.

   when your buying 84 penguins for $13597, you are paying [$13,597 ÷ 84] per penguin; which is $161.87

   when your buying 50 penguins for $795.95, you are paying [$795.95 ÷ 50] per penguin; which is $15.92
    ∴ in this case, it is better to buy  50 penguins for $795.95

15) when you buy 48oz big gulp for $1.39, you're paying [$1.39 ÷ 48] per oz; which is $0.029
      when you buy 32oz of coke for $0.89, you're paying [$0.89 ÷ 32] per oz; which is $0.028.
      ∴ by technicality, buying 48oz of big gulp would be more expensive than buying 32 oz of coke. (but logically the difference is negligible but I guess it adds up in the long run).

If 3 pizza cost $19.99, then each pizza cost   $19.99 ÷ 3 = $6.66

If 12 chickens lay 30 eggs, then each chicken would lay 30 ÷ 12 = 2.5 eggs per chicken