Answer
5000, Yes.
Work Step by Step
Evaluate the determinant with cofactors:
$\begin{array}( \\|A|= \\ \\ \end{array}
\begin{vmatrix} 30 & 0 &20\\0 &-10 &-20\\40 &0 &10\end{vmatrix} \begin{array}( \\=30 \\ \\\end{array}\begin{vmatrix} -10 &-20\\0 &10 \end{vmatrix} \begin{array}( \\+20 \\ \\\end{array}
\begin{vmatrix} 0 &-10\\40 &0 \end{vmatrix}$
$|A|=30(-100)+20(400)=5000$
As $|A|\ne0$, the matrix should have an inverse.
