\(a,\Leftrightarrow\left\{{}\begin{matrix}a+2=3-a\\b\ne-1\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}a=\dfrac{1}{2}\\b\ne-1\end{matrix}\right.\\ b,\Leftrightarrow\left\{{}\begin{matrix}a+2=3-a\\b=-1\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}a=\dfrac{1}{2}\\b=-1\end{matrix}\right.\)