What Is 16 - 8x divided by 4

(16 - 8x)/4 = 4(4 - 2x)/4
= 4 - 2x
Now in your question it seems to be asking for the x intercept, so I'll go ahead and solve that too:
8x - 4y = 16
-4y = -8x + 16
y = 2x - 4
0 = 2x - 4
4 = 2x
x = 2
The x-intercept is 2 and the y-intercept is -4.