Someone help me with this please

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.

The amount spent on food and drink by 20 customers is shown below what is the modal amount spent ?

Triangle knm is what is true about the sides of knm