Solve the system of linear equations if possible. If there is no solution, enter NONE for both $x$ and $y$. If there are infinitely many solutions, enter $x$ for $x$ and an expression in terms of $x$ for $y$ (i.e. solve for $y$).

\begin{cases} y-x &= 12 \\ 5 y + 10 x &= -15 \end{cases} $x=$
$y=$