Answer:
[tex]\large\boxed{B.\ (f+g)(x)=5x+3}[/tex]
Step-by-step explanation:
[tex](f+g)(x)=f(x)+g(x)\\\\\text{We have:}\ f(x)=2x-6\ \text{and}\ g(x)=3x+9.\\\\\text{Substitute:}\\\\(f+g)(x)=(2x-6)+(3x+9)=2x-6+3x+9\\\\\text{combine like terms}\\\\(f+g)(x)=(2x+3x)+(-6+9)\\\\(f+g)(x)=5x+3[/tex]
