\(=\frac{x+y+z}{2\left(x+y+z\right)}=\frac{1}{2}\)
\(\Rightarrow\left\{{}\begin{matrix}x+y+z=6\\2x=y+z-3\\2y=x+z\\2z=x+y+3\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}x+y+z=6\\3x=x+y+z-3\\3y=x+y+z\\3z=x+y+z+3\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}3x=6-3\\3y=6\\3z=6+3\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}x=1\\y=2\\z=3\end{matrix}\right.\)