Edited : I apologise I misunderstood the question.
You can solve the equation.
Answer:

Step-by-step explanation:
we know that
The given equation y=5 is a horizontal line (is parallel to the x-axis)
The slope of the given line is equal to zero
A perpendicular line to the given line is a vertical line (parallel to the y-axis)
so
The equation of a vertical line is equal to the x-coordinate of the point that passes through it
The point that passes through it is (-4,-6)
therefore
The equation of the perpendicular line is

Answer:
y= -a*x + 12
<u> </u><u> </u><u> </u><u> </u><u> </u><u> </u><u>b</u><u> </u><u> </u><u> </u><u> </u><u> </u><u> </u><u> </u><u> </u><u>b</u>
Step-by-step explanation:
ax+by=12 (subtract "ax" from both sides so that the one on the left will become zero and we will have "by" )
by= -ax+12(divide both side by "by" so that we will have the equation as "y=mx+b")
finally the result will be:
y= -a*x + 12
b b