$${\left({\mathtt{10}}{\mathtt{\,-\,}}{\mathtt{y}}\right)}^{{\mathtt{2}}}{\mathtt{\,\small\textbf+\,}}{{\mathtt{y}}}^{{\mathtt{2}}} = {\mathtt{212}} \Rightarrow \left\{ \begin{array}{l}{\mathtt{y}} = -{\mathtt{4}}\\
{\mathtt{y}} = {\mathtt{14}}\\
\end{array} \right\}$$
.
