This problem is about function composition. That is one function inside another.
We need to find
[tex](g\circ f)(x)[/tex]This indicates we have to substitute f(x) inside g(x), as follows.
[tex]\begin{gathered} g(x)=-x-4 \\ g(f(x))=-(2x)-4=-2x-4 \end{gathered}[/tex]Therefore, the composition is
[tex](g\circ f)(x)=-2x-4[/tex]