A bird flies linearly, according to the equation

(x,y,z) = (5,6,7) + t[2,3,1]. Assume that the Sun is directly overhead , making the Sun's rays perpendicular to the xy-plane which represents the ground. The birds shadow is said to be projected perpendicularly onto the level ground. Find an equation that describes the motion of the shadow.

I got y=3/2x- 3/2

I am not sure about my answer.