Hello from MrBillDoesMath! 
 
Answer: 
y = (1/8)x + 5 
Discussion: 
 The slope (m) of y = -8x +4 is -8. The slope of the perpendicular lines is the negative reciprocal of the slope of the first line. That is, the perpendicular slope is -1 /(-8) = + 1/8
y = (1/8) x + b (*)
Also, the perpendicular line passes through the point (0.5) so substituting these values in (*) gives
5 = (1/8)(0) + b => as (1/8) 0 = 0
5 = b
The perpendicular line is given by y = (1/8)x + 5
Thank you, 
 
MrB