A notable source of income for movie theatre owners comes from food sales at their concession stands. Suppose the demand for medium-sized popcorn servings on Saturday nights at movie theaters is: Qd = 200 - 15Pp + 2Pn - 5Pc. In this equation, Pp is the price per medium-sized popcorn; Pn is the price per serving of nachos; and Pc is the price per bag of candy. From the information in the equation, determine whether nachos are substitutes or complements for popcorn. Is candy a substitute or complement for popcorn? Briefly explain each answer.

Assume that the supply curve for popcorn is determined by the following: Qs=12Pp. Assume further that today's price of nachos is $6 per serving and of candy is $4 per bag. Determine the equilibrium quantity exchanged and price of popcorn.

Next consider the more general relationship between the price of popcorn and the price of candy. Assuming that the price of nachos continues to be $6 per serving, but allowing the price of candy to vary, find an expression for the equilibrium price of popcorn as a function of the price of candy.