A variable needs to be eliminated to solve the system of equations below. Choose the correct first step. \[ \begin{array}{c} -x-6 y=51 \\ -x+10 y=-109 \end{array} \] Answer Subtract to eliminate $\mathbf{x}$. Add to eliminate $\mathbf{y}$. Subtract to eliminate $\mathbf{y}$. Add to eliminate $\mathbf{x}$. Submit Answer

Step 1 ：The system of equations is already set up in a way that makes it easy to eliminate x. If we add the two equations together, the x terms will cancel out, leaving us with an equation in terms of y. This seems like the correct first step.

Step 2 ：The equations are added together to eliminate x, resulting in a new equation in terms of y. The solution for y is -29/2. This confirms that the correct first step to solve the system of equations is to add the two equations together to eliminate x.

Step 3 ：Final Answer: \(\boxed{\text{Add to eliminate } x}\)