Answer
$a.\quad 4,$
$b.\quad 7,$
$c.\quad 8.$
Work Step by Step
If $g$ has an inverse, and
(a,b) is on the graph, this means that $g(a)=b$ and $g^{-1}(b)=a.$
The point $(4,2)$ is on the graph, so $g^{-1}(2)=4$
The point $(7,5)$ is on the graph, so $g^{-1}(5)=7$
The point $(8,6)$ is on the graph, so $g^{-1}(6)=8$
