Answer
The answer is $ 26$.
Work Step by Step
We know that for a matrix
$ \begin{bmatrix}
a & b\\
c & d
\end{bmatrix}$
the determinant is $ D=ad−bc $.
the given determinant is
$ \begin{vmatrix}
1 & 3\\
-8 & 2
\end{vmatrix} $
Hence, $D=1 \cdot 2-3\cdot (-8) =2+24=26 $.
