Can I watch Friends on Hulu? If so what type of subscription do I need? Will give brainliest

Ineed with number 17 i don’t get it at alll

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.

Find the value of x that will make l ll m