Find the Inverse of the Matrix $\left[ \begin{array} { c c } 3 & 6 \\- 9 & - 15\end{array} \right]$

Multiple Choice

Find the inverse of the matrix $\left[ \begin{array} { c c } 3 & 6 \\- 9 & - 15\end{array} \right]$ .

A) $\frac { 1 } { 7 } \left[ \begin{array} { c c } 3 & 6 \\- 9 & - 15\end{array} \right]$
B) $\frac { 1 } { 3 } \left[ \begin{array} { c c } - 5 & - 2 \\3 & 1\end{array} \right]$
C) $\left[ \begin{array} { c c } - 3 & - 6 \\15 & 9\end{array} \right]$
D) $\left[ \begin{array} { c c } 3 & - 9 \\12 & - 21\end{array} \right]$
E) $\frac { 1 } { 13 } \left[ \begin{array} { l l } - 3 & - 6 \\- 9 & 15\end{array} \right]$