Answer
$-12$
Work Step by Step
We know that for a matrix
\[
\left[\begin{array}{rrr}
a & b & c \\
d &e & f \\
g &h & i \\
\end{array} \right]
\]
the determinant, $D=a(ei-fh)-b(di-fg)+c(dh-eg).$
Hence here $D=2(6\cdot1-9\cdot3)-(-1)(-3\cdot1-9\cdot-2)+5(-3\cdot3-6\cdot-2)=2(-21)+1(15)+5(3)=-12.$
