Okay, just put in y=mx+b form, then the slope would be m.
SO, first what you have to do is arrange it so y and x are not on the same side of the equation.
SO, what you could do first is add 3y to both sides of the equation, giving you 4x = 8 + 3y.
Now subtract 8 on both sides, giving you 4x - 8 = 3y.
Now divide by 3 on both sides, giving you ((4x)/3) - (8/3) = y, or y = ((4/3)x - (8/3).
SO, now that we have it in y=mx+b form, you can see that the slope is (4/3).