We have the following system of equations:

The linear combintation method is a process of adding two algebraic equations so that one od the variables is eliminated.
In this regard, by multiplying the second equation by -1, we obtain an equivalent system of equations:

Then, by adding both equations, we can eliminate the variable y, that is,

Once we know the result for x, we can substitute its values into one of the orginal equations. Then, if we substitute x=-1 into the first equation, we have

which gives

Therefore, the solution is ( -1, 7), which corresponds to the last option.