What is the value of two cubed?

Acable car begins its trip by moving up a hill. as it moves up, it gains elevation at a constant rate of 50 feet/minute until it reaches the peak at 2,000 feet. then, as the car moves down to the hill’s base, its elevation drops at the same rate.

Can someone me with my hwplz(only the circled ones)

Solve the system of equations. y= 2x y= x^2 - 15