Can someone help? i’m really confused

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.

Solve the given system of equations. 2y= -x+9 , 3x-6= -15

Need 50 will mark brainliest answer. find the lengths of all the sides and the measures of the angles.