given expression to simplify,
[tex]q^{-3}r^0s^{-1}\cdot\: q^3r^{-9}s^0[/tex][tex]\begin{gathered} q^{-3}r^0s^{-1}\cdot\: q^3r^{-9}s^0 \\ q^{-3}\cdot q^3=1 \\ \: =r^0s^{-1}r^{-9}s^0 \\ =1\cdot\frac{1}{r^9}s^{-1}s^0 \\ =1\cdot\frac{1}{r^9}\cdot\frac{1}{s} \\ =\frac{1}{r^9}\cdot\frac{1}{s} \\ =\frac{1}{r^9s} \\ =r^{-9}s^{-1} \end{gathered}[/tex]
