From the street, you drive down 6 levels in a parking garage. when you leave, you drive back up 6 levels. which expression represents the number of levels you are from the street?

Arrange the parabolas represented by the equations in increasing order with respect to the y-values of their directrixes. y = -x2 + 3x + 8 y = 2x2 + 15x + 18 y = x2 + 13x + 5 y = -2x2 + 4x + 8