y = -1/4x + 4 ==> This is in slope-intercept form, and we want it in standard form.
Remember, standard form is ax + by = c
Where a = x, b = y, and c = the numerical variable / sign.
So, basically all we have to do is move x to the left side, so that x and y are together.
To do that, we have to add 1/4x to both sides.
1/4x + y = 4
We want to make x into a regular number (not a fraction) so we multiply both sides by 4.
4(1/4x + y) = 4(4)
Simplify.
x + 4y = 16
Divide 4y and 16 by 2.
x + 2y = 8
So, your answer is C.
~Hope I helped!~