Question 309460
Find the coordinate when you know the slope. 
m = 6 
(7, 5) (r, 9)
.
Plug above values into "point-slope" form of a line:
y - y1 = m(x - x1)
9 - 5 = 6(r - 7)
4 = 6(r - 7)
4 = 6r - 42
46 = 6r
46/6 = r
23/3 = r