5/6 - 2/6 in simplest form

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 anyone me with 32,33,36,37,and 40.

Collin did the work to see if 10 is a solution to the equation r/4=2.4