Answer
$$-15.$$
Work Step by Step
$$
\left|\begin{array}{rrr}{1} & {0} & {1} \\ {-2} & {0} & {3} \\ {1} & {3} & {-1}\end{array}\right|=\left|\begin{array}{rrr} {0} & {3} \\ {3} & {-1}\end{array}\right|-0+\left|\begin{array}{rrr}{-2} & {0} \\ {1} & {3} \end{array}\right|\\
=-9-6=-15.
$$
