NEED HELP PLEASE ONLY GOT 20 min

Use the elimination method to solve the system of equations -x+5y=-4 and 4x+3y=16

Find the value of tan theta if sin theta = 12/13 and theta is in quadrant 2

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.