Hi, everyone how are you today yesterday i have finish all my questions it’s was 30 question and this is new question can me i want to finish before the night because in the night the website will be closed so me

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.