Answer:
y = -9
Step-by-step explanation:
perpendicular to the y-axis means it is parallel to the x-axis.
so, it is a flat line, which means the slope is 0 (it has the save y value for every x value).
therefore the equation is
y = 0×x + b
of simply
y = b
to get b we look at the point we know about (0, -9).
-9 = b
aha !
so, the line equation is simply
y = -9
