Answer
$-2$
Work Step by Step
Based on the graph, the $y-$value of $f$ at $x=4$ is $2$. Hence, $f(4)=2.$ The $y-$value of $f$ when $x=2$ is $-2$. Hence, $f(2)=-2$. The given composition function, $
(f\circ F)(4)
,$ evaluates to
\begin{array}{l}\require{cancel}
f(f(4))
\\\\=
f(2)
\\\\=
-2
.\end{array}