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