Start off with the given information. The question states that the x-int. is 4, so you should recognize that there is a point at (4,0). Plug the point into the equation.
k(4) + 2(0) + 8 = 0
Now simplify the equation.
4k + 0 + 8 = 0
Isolate the variable, make sure it's on its own side.
4k = 8
Now get the k by itself to solve the equation. Divide both sides by 4.
