Answer
$f(-3)=5$
$f(0)=8$
$f(5)=13$
Work Step by Step
The given function is
$f(x)=x+8$.
Substitute $x=-3$.
$\Rightarrow f(-3)=-3+8$
$\Rightarrow f(-3)=5$
Substitute $x=0$.
$\Rightarrow f(0)=0+8$
$\Rightarrow f(0)=8$
Substitute $x=5$.
$\Rightarrow f(5)=5+8$
$\Rightarrow f(5)=13$
