## Precalculus (6th Edition) Blitzer

The equation is, $11x+4y=-3$.
By multiplying equation (II) by 2 and adding into equation (I), we get: \begin{align} & 5x-2y-4z=3 \\ & \underline{6x+6y+4z=-6} \\ & \underline{11x+4y+0z=-3} \\ \end{align} Thus, the equation becomes $11x+4y=-3$.