Please help me, eshay lad

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.

Me with this one question, and i'll upvote the brainliest answer

What is the measure of angle tvu shown in the diagram below