$$\underset{\,\,\,\,{\textcolor[rgb]{0.66,0.66,0.66}{\rightarrow {\mathtt{}}}}}{{solve}}{\left(\begin{array}{l}{\mathtt{2}}={\mathtt{1}}\\
{\mathtt{1}}={\mathtt{2}}\\
{\mathtt{2}}{\mathtt{\,\small\textbf+\,}}{\mathtt{2}}={\mathtt{1}}{\mathtt{\,\small\textbf+\,}}{\mathtt{1}}\\
{\mathtt{2}}{\mathtt{\,\small\textbf+\,}}{\mathtt{2}}={\mathtt{2}}\end{array}\right)}$$
