Vertical lines take the form of and horizontal lines take the form of
Why is this? Notice that whenever you make a horizontal line on a graph and select virtually any point that's on that line, all of the points you pick will have the same y value. Try to imagine the same thing with a vertical line, are the results the same?
So the line (we got -12 from the coordinate that was given to us on the question prompt) is a vertical line that passes through virtually all possible y values (from positive infinity to negative infinity, or vice-versa) which means that the question prompt having given us the y value was negligible.
