Answer
$-42$
Work Step by Step
Since, we have $D=\begin{vmatrix}\begin{vmatrix}3&1\\-2&3\end{vmatrix}\begin{vmatrix}7&0\\1&5\end{vmatrix}\\\begin{vmatrix}3&0\\0&7\end{vmatrix}\begin{vmatrix}9&-6\\3&5\end{vmatrix}\end{vmatrix}$
or, $=\begin{vmatrix}9+2&35-0\\21-0&45+18\end{vmatrix}$;
or, $=\begin{vmatrix}11&35\\21&63\end{vmatrix}$;
or, $=-42$
