Answer
See proof
Work Step by Step
We are given the functions:
$f(x)=x+5$
$g(x)=x-5$
Determine $f\circ g$:
$(f\circ g)(x)=f(g(x))=f\left(x-5\right)=(x-5)+5=x$
Determine $g\circ f$:
$(g\circ f)(x)=g(f(x))=g\left(x+5\right)=(x+5)-5=x$
We got:
$(f\circ g)(x)=(g\circ f)(x)=x$
