We have the line:
We have to find a perpendicular line that passes through point (-5,4).
As the original line is an horizontal line (slope = 0), a perpendicular line will be a line that is vertical (undefined slope) with an equation x = k, where k is a constant.
Then, as x = k defines the line that pass through all the points with coordinates (k,y), if it has to pass through (-5,4), then k = -5.
If k = -5, the line is x = -5.
We can picture this in a graph as:
Answer: the equation is x = -5.