For the Given Functions F(x) and G(x), Find (F $f(x)=-5 x+8, g(x)=x^{2}-3 x-9$

For the given functions f(x) and g(x) , find (f + g) (x) or (f - g) (x) as indicated
- $f(x) =-5 x+8, g(x) =x^{2}-3 x-9$
Find $(f+g) (x)$ .

A) $x^{2}+3 x-1$
B) $x^{2}-8 x-1$
C) $x^{2}-8 x+12$
D) $x^{2}+3 x+5$