A line perpendicular to the x-axis is a vertical line.
In a vertical line, every point has a different y-coordinate and the same x-coordinate. Since you want a line that is vertical and passes through the point (5, -3), then every point on the line must have x-coordinate 5 no matter what its y-coordinate is. The slope of a vertical line is undefined.
Answer: The equation is x = 5; the slope is undefined
