Answer:
See Explanation
Explanation:
Missing in the question is the slope of line r.
We'll assume that the slope (m) of line r is

When two lines are perpendicular, their slope are related in:




The equation of the (3,-6) is:

Where

So:


Make y the subject


Please note that this answer might be incorrect to you based on the assumed value. However, the step will guide you in solving similar questions