`((a^-2)/(b^2))^-3((a^-3)/(b^5))^2`

`=(1/(a^2b^2))^-3(1/(a^3b^5))^2`

`=(a^2b^2)^3(1/(a^3b^5))^2`

`=(a^6b^6)/(a^6b^10)`

`=(b^6)/(b^10)`

`=1/(b^4)`

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