Whats two minus three

Fast phone couldn’t copy and paste so i decided to right it down

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.

What is the range for 31,39,29,34,37,24,36,33,34,28