Answer
$-169$
Work Step by Step
The determinant for a 3 by 3 matrix can be computed as: $Determinant (D)= \begin{vmatrix} A & B & C \\
a & b & c \\
g &h & i \\ \end{vmatrix}=A(ei-fh)-B(di-fg)+C(dh-eg)$
Therefore, $D=1 [(1) (3) -(2)(-5)]-3[6(3)-(8)(-5)]+(-2)[(6)(2)-(1)(8)]\\=(1)(13) -(3)(58)+(-2)(4) \\=13-174-8 \\=-169$