Given the augmented matrix $$A = \left\lbrack \begin{array}{rrr|r} 1 & 2 & 6 & -4 \\ 2 & 5 & 3 & -1 \\ -3 & -8 & 1 & -1 \end{array} \right\rbrack,$$ perform each row operation in the order specified and enter the final result.

First: $R_2 - 2 R_1 \to R_2$,
Second: $R_3 + 3 R_1 \to R_3$,
Third: $R_3 + 2 R_2 \to R_3$.