Answer: z = -8
Explanation:
A line with an "undefined slope" is one that is vertical to the x axis. It has a slope that is undefined because there is no change in x for all points on the line. The slope is the Rise over the Run, and in this case there is no :Run." That means dividing by zero, so it is undefined.
Since x foes not change, the unknown point (z,2) would be (-8,2).
z = -8