How do you multiply (x^ { - 3} y ^ { - 1} ) ^ { - 1} ( x ^ { - 3} y ^ { 0} ) ^ { 2}?

The Answer is ${x}^{-} 3 y$.
1. ${\left({x}^{-} 3 {y}^{-} 1\right)}^{-} 1$ = ${x}^{3} y$
2. ${\left({x}^{-} 3 {y}^{0}\right)}^{2}$ = ${x}^{-} 6 {y}^{0}$ = ${x}^{-} 6$ because ${y}^{0}$ = 1.
therefore the answer becomes $\left({x}^{3} y\right) \left({x}^{-} 6\right)$ = ${x}^{-} 3 y$