Answer:
r=5
Explanation:
The gradient(m) can be found using (y2-y1)/(x2-x1)
if we make the substitution given the points in the question, we find
(r--4)/(-5--3)
this simplifies to
(r+4)/-2
since we know that m= -9/2, we can make an equation
(r+4)/-2=-9/2
multiply both sides of the equation by -2
r+4=9
r=5