Answer
$f^{-1}(0)=2$
Work Step by Step
RECALL:
(1) If $(a, b)$ is on the graph of $f(x)$, then $f(a) = b$.
(2) If $f(a)=b$, then $f^{-1}(b)=a$
The given graph contains $(2, 0)$
This means that $f(2) = 0$.
Thus, $f^{-1}(0)=2$.