To find the perpendicular slope, take the slope you have, change it’s sign, and flip it upside down.
5 -> -5 (change its sign)
-5 -> -1/5 (flip it upside down)
Perpendicular slope is -1/5.
Remember a whole number can be treated as that whole number over 1.
5 = 5/1
That allows you to flip it.
