Answer
$a.\quad 6,$
$b.\quad 2,$
$c.\quad 0.$
Work Step by Step
If f has an inverse, and
(a,b) is on the graph, this means that $f(a)=b$ and $f^{-1}(b)=a.$
The point $(6,2)$ is on the graph, so $f^{-1}(2)=6$
The point $(2.5)$ is on the graph, so $f^{-1}(5)=2$
The point $(0,6)$ is on the graph, so $f^{-1}(6)=0$
