Question

(r, 2), (6, 3) , m = 1/2

Answer 1

As two points are given and the slope between two points say (a,b),(x,y) and is given by
m=y-b/x-a

For your question

1/2=3-2/6-r
(6-r)=1(2)
6-r=2
r+2=6
r=4