### Perform the indicated operation(s) on the matrix.

\(\left[\begin{array}{rrr|r}-2 & 1 & 0 & 0 \\
-5 & 3 & 0 & -2 \\
-2 & -4 & -4 & 20\end{array}\right]\begin{array}{ll}\phantom{1} & -\frac{1}{2}R_1 \to R_1 \\
\phantom{1} & \\
\phantom{1} & \end{array}\)