As you have written it, I will assume that your equation reads....
y=(3/2)x-4.........given equation Eq1, problem statement
Recognize that this equation is already in "slope-intercept" form
(y=mx+b), slope is "m" and the y-intercept is "(0,b)."
So the slope and y-intercept of Eq1 is...
m=3/2
y-intercept=(0,-4)
The slope of a perpendicular line to Eq1 "m⊥" is the "negative
inverse" of the slope "m" of Eq1. So....
m⊥=-(1/m)
=-(1/(3/2))
=-2/3
Andrew M.
12/07/15