[tex]\left\{\begin{array}{ccc}3x+6y=-9&\text{divide both sides by (-3)}\\x+2y=-3\end{array}\right\\\\\underline{+\left\{\begin{array}{ccc}-x-2y=3\\x+2y=-3\end{array}\right}\qquad\text{add both sides of the equations}\\. \qquad\qquad0=0\qquad TRUE\\\\Answer:\ \boxed{\text{Infinitely many solutions}}\\\\\left\{\begin{array}{ccc}x\in\mathbb{R}\\y=-\dfrac{1}{2}x-\dfrac{3}{2}\end{array}\right[/tex]
