a)
64^{-\frac{2}{3}}=(4^3)^{-\frac{2}{3}}=4^{-2}=(\frac{1}{4})^2=\frac{1}{16}
b)
125^{\frac{2}{3}}=(5^3)^{\frac{2}{3}}=5^2=25
c)
8^{\frac{2}{3}}=(2^3)^{\frac{2}{3}}=2^2=4
d)
{\frac{9}{9^{-\frac{4}{5}}}=\frac{3^2}{(3^2)^{-\frac{4}{5}}}=\frac{3^{\frac{10}{5}}}{3^{-\frac{8}{5}}}=3^{\frac{10}{5}-(-\frac{8}{5})}=3^{\frac{18}{5}}=3^{3\frac{1}{5}}=3^3 \cdot 3^{\frac{1}{5}}=27\sqrt[5]{3}}
e)
4^{\frac{2}{3}}=(4^2)^{\frac{1}{3}}=16^{\frac{1}{3}}=\sqrt[3]{8\cdot 2}=2\sqrt[3]{2}
f)
3\sqrt{2x^2y}=3x\sqrt{2y}
g)
(-8)^{-3}=[(-2)^3]^{-3}=(-2)^{-9}=(-\frac{1}{2})^9=-\frac{1}{512}
h)
27^{-\frac{2}{3}}=(3^3)^{-\frac{2}{3}}=3^{-2}=(\frac{1}{3})^2=\frac{1}{9}