This would be a question best answered through drawing a graph.
The graph of y = 11 is a straight line through the Y axis at 11 (horizontal line).
Therefore you know the equation of the next line must be a vertical line (perpendicular).
The general formula for a vertical line will be x = ?
The coordinate you have (4, -6) shows you that x = 4 when y = -6.
Therefore the formula for the line must be x=4.
x = 4 will be a straight vertical line passing through 4 on the x axis. It will also then pass through the point (4, -6)