For this case we have to by definition, if two lines are perpendicular then the product of its slopes is -1. That is to say:

We have the following equation:

Thus, the equation is of the pending-intersection form

Where:
m: It's the slope
b: It is the cut-off point with the y axis
We have to:

Thus, we find
:

Thus, the slope of the line perpendicular to the given line is:

ANswer:
