You can put this solution on YOUR website! Find the value of x so that the slope of the line through (2,9) and (x,-3) is 3/8.
-----------------------------------------
slope = diffy/diffx
---
3/8 = (-3-9)/(x-2) = -12/(x-2)
3(x-2) = -96
x-2 = -32
x = -30