Answer:
[tex]\frac{ {b}^{10} }{ 81 {a}^{2} } [/tex]
Step-by-step explanation:
[tex](9ab^{-5})^{-2} \\ \\ = {9}^{ - 2} {a}^{ - 2} {b}^{ - 5( - 2)} \\ \\ = {9}^{ - 2} {a}^{ - 2} {b}^{10} \\ \\ = \frac{ {b}^{10} }{ {9}^{2} {a}^{2} } \\ \\ \huge = \frac{ {b}^{10} }{ 81 {a}^{2} } [/tex]
