You give up too easily.
I posted how to get the answer below at the original question.
OK but I replied...
As did I.
Maybe you do understand this for horizontal lines.
If you interchange x with y, vertical and horizontal lines are interchanged (you reflect everything in the line x = y)
If the question is:
"Write the equation of a horizontal line passing through the point (-4,8)",
then I think you understand that the equation is:
y = 8,
which you can write as:
y = 8 + 0 x
where the zero is the slope of the line.
If you interchage x with y the horizontal line becomes a vertical line and the equation ecomes:
x = 8