Answer
6
Work Step by Step
We are given that $f(x)=x^{2}-9$, $g(x)=2x$, and $h(x)=x-3$.
We are asked to find the value of $(f+g)(3)$. We know that $(f+g)(x)=f(x)+g(x)$.
Therefore, $(f+g)(3)=((3)^{2}-9)+(2(3))=(3^{2}-9)+(2\times3)=(9-9)+(6)=(0)+6=6$.