Answer:
x = 40 is actually a vertical line.
Explanation:
Let (x, y) where x = 40. We will get (40,y).
Because there is no y-term or y-value. We can say that y is the set of all real numbers. That makes the graph a vertical.
A horizontal line would be y = b where b is a constant. We call y = b the Constant Function where the graph is a horizontal line.