Answer:
-1/6
Step-by-step explanation:
First find the slope of the line through the points
m = (y2-y1)/(x2-x1)
= (-4-8)/(1-3)
= -12/-2
=6
Now we need to find the slope of the line that is perpendicular
Perpendicular lines multiply to -1
6 * mp = -1
mp = -1/6