Please help will ill brainiest if correct

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 measure of angle tvu shown in the diagram below

Solve this equation using substitution. {4x + y = −2} {4x + 6y = 44}