[tex]\bf \begin{cases}
f(x)=x+2\\
h(x)=x+5\\
h(x)=(f\circ g)(x)
\end{cases}\quad (f\circ g)(x)\implies \stackrel{h(x)}{f(~g(x)~)}
\\\\\\
\stackrel{h(x)}{f(~~g(x)~~)}=g(x)+2=\stackrel{h(x)}{x+5}\implies g(x)+2=x+5
\\\\\\
g(x)=x+5-2\implies \boxed{g(x)=x+3}[/tex]
