a fountain on a lake sprays water in a parabolic arch modeled by the equation y = -0.3x^2 + 3x. a beam of light modeled by the equation -2x + 5.5y = 19.5 passes through the fountain to create a rainbow effect. if the beam cuts the water spray at points a and b, such that point b is at a higher level than point a, what distance from the ground level is point a?