a)
6^{-1}=(\frac{1}{6})^1=\frac{1}{6}
b)
(-9)^{-1}=(-\frac{1}{9})^1=-\frac{1}{9}
c)
(\frac{2}{3})^{-1}=(\frac{3}{2})^1=\frac{3}{2}=1,5
d)
(-2)^{-5}=(-\frac{1}{2})^5=-\frac{1}{32}
e)
(-\frac{1}{3})^{-3}=(-3)^3=-27
f)
(-\frac{2}{5})^{-2}=(-\frac{5}{2})^2=\frac{25}{4}=6\frac{1}{4}