simplify
(265)^-(-3/4^2)

Dear student,
Your question appears to be unclear.
I am assuming it to be, (256)^-3/4
Here is the solution.
$$\begin{gathered} {\left(256\right)}^{-3/4} \\ \mathrm{Here} \mathrm{is} \mathrm{the} \mathrm{solution}. \\ {\left(256\right)}^{-3/4} \\ ={\left(4\times 4\times 4\times 4\right)}^{-3/4} \\ ={\left[{\left(4\right)}^4\right]}^{-3/4} \\ ={\left(4\right)}^{-3} \\ =\frac{1}{{\left(4\right)}^3} \\ =\frac{1}{64} \end{gathered}$$