To find the x intercept, you need to set the equation equal to y.
2y=-8x+4
y=-4x+2
Then, you need to set y as zero and solve for x, since you are trying to find the x value when y is 0 (x-intercept).
0=-4x+2
-2=-4x
2=4x
x=1/2
The x-intercept is (1/2, 0).