You would do 310/5, which is 62.
The line y = -3 is a horizontal line. The perpendicular line will be vertical, so will have an equation of the form
x = c
for some constant c.
You want the vertical line to go through the point (4, -6), so the required value of c is the x-value of that point: 4
Your equation is
x = 4
(8x^2+2x+8)+(3x^3+7x+4)=
8x^2+2x+8+3x^3+7x+4
3x^3+8x^2+(2+7)x+12=
3x^3+8x^2+9x+12
Answer: Option A. 3x^3+8x^2+9x+12