Question

The equation of line CD is (y−3) = − 2 (x − 4). What is the slope of a line perpendicular to line CD?
a. 1 over 2
b. 2
c. negative 1 over 2
d. −2

Answer 1

$(y-3)=-2(x-4) \\ y-3 = -2x+8 \\ y=-2x+11$
Slope: -2

NOTE: The line perpendicular to line $y=mx+b$ has a slope $-\dfrac{1}{m}$. 

So your slope is $-\dfrac{1}{-2}=\dfrac{1}{2}$   -  1 over 2  (Answer a)