Answer:
[tex]\frac{1}{729} c^{27}[/tex]
Step-by-step explanation:
[tex]\left(9c^{-9}\right)^{-3}=\frac{1}{\left(9c^{-9}\right)^3}[/tex]
[tex]\frac{1}{9^3\left(c^{-9}\right)^3}[/tex]
[tex]\frac{1}{729c^{-9\times 3}}[/tex]
[tex]\frac{1}{729c^{-27}}[/tex]
[tex]\frac{c^{27}}{729}=\frac{1}{729} c^{27}[/tex]
