+4 $${\mathtt{8}}{\mathtt{\,\times\,}}{\mathtt{y}}{\mathtt{\,\small\textbf+\,}}{\mathtt{5}}{\mathtt{\,\times\,}}{\mathtt{x}}{\mathtt{\,-\,}}{\mathtt{3}}{\mathtt{\,\times\,}}{\mathtt{y}}{\mathtt{\,\small\textbf+\,}}{\mathtt{7}}{\mathtt{\,-\,}}{\mathtt{2}}{\mathtt{\,\times\,}}{\mathtt{x}} = {\mathtt{5}}{\mathtt{\,\times\,}}\left(\underset{{\tiny{\text{Error: Unknown Identifier}}}}{{\mathtt{x}}}\right){\mathtt{\,\small\textbf+\,}}{\mathtt{8}}{\mathtt{\,\times\,}}\left(\underset{{\tiny{\text{Error: Unknown Identifier}}}}{{\mathtt{y}}}\right){\mathtt{\,-\,}}{\mathtt{2}}{\mathtt{\,\times\,}}\left(\underset{{\tiny{\text{Error: Unknown Identifier}}}}{{\mathtt{x}}}\right){\mathtt{\,\small\textbf+\,}}{\mathtt{7}}{\mathtt{\,-\,}}{\mathtt{3}}{\mathtt{\,\times\,}}\left(\underset{{\tiny{\text{Error: Unknown Identifier}}}}{{\mathtt{y}}}\right)$$
