Answer:
Option D is correct ...
Step-by-step explanation:
because f(x) is defined on x<0 which is only possible in log(-x)
So we have the equation:

Then we need to multiply by 4 on both sides to get rid of the denominator on the left:

Then we subtract 9 on both sides to solve for z:

Therefore the answer is z = -0.6.
I don't know the official answer but I can confirm for you that it is either C or D. I just don't remember how to determine which way the sign goes. Sorry
The answer would be -37.5