Solve Each System by Using Either the Substitution or the Elimination-By-Addition

Short Answer

Solve each system by using either the substitution or the elimination-by-addition method, whichever seems more appropriate. $$\left( \begin{array} { c } 6 x - 9 y = 27 \\- 6 x + 2 y = - 6\end{array} \right)$$