How do I go about solving this?

Answer:
Option B is correct.
Step-by-step explanation:
we are given [tex]f(x) = \frac{x}{2}-3[/tex]
and [tex]g(x) = 3x^2+x-6[/tex]
We need to find (f+g)(x)
We just need to add f(x) and g(x)
(f+g)x = f(x) + g(x)
[tex](f+g)(x)=(\frac{x}{2}-3)+(3x^2+x-6)\\(f+g)(x)=\frac{x}{2}-3+3x^2+x-6\\(f+g)(x)=3x^2+\frac{x}{2}+x-3-6\\(f+g)(x)=3x^2+\frac{3x}{2}-9\\[/tex]
So, Option B is correct.
For this case we have the following functions:
[tex]f (x) = \frac {x} {2} -3\\g (x) = 3x ^ 2 + x-6[/tex]
We must find [tex](f + g) (x).[/tex] By definition, we have to:
[tex](f + g) (x) = f (x) + g (x)[/tex]
So:
[tex](f + g) (x) = \frac {x} {2} -3+ (3x ^ 2 + x-6)\\(f + g) (x) = \frac {x} {2} -3 + 3x ^ 2 + x-6\\(f + g) (x) = + 3x ^ 2 + x + \frac {x} {2} -3-6\\(f + g) (x) = + 3x ^ 2 + \frac {2x + x} {2} -9\\(f + g) (x) = + 3x ^ 2 + \frac {3x} {2} -9[/tex]
Answer:
Option B