Suppose that a when a cell phone store charges 16$ for a car charger, it sells 92 units. when it drops the price to 15$ it sells 96 units. assume that demand is a linear function of price.

if each phone charger costs 1$ to make, what price should the store charge to maximize its profit?
if x is the number of times the price is reduced by one dollar.

find a function for total profit with respect to x. a negative value for x will mean the price is increased.