What is the quotient of 2^4/2^-4

Which expression is equivalent to7_/x^2 ÷ 5_/y^3? assume y# 0

Suppose that the price p (in dollars) and the weekly sales x (in thousands of units) of a certain commodity satisfy the demand equation 4p cubedplusx squaredequals38 comma 400. determine the rate at which sales are changing at a time when xequals80, pequals20, and the price is falling at the rate of $.20 per week.

Can someone answer this question? : )