Answer
(a) $\frac{(5a)^{-2}}{(5a)^2}=\frac{1}{(5a)^4}=\frac{1}{625a^4}$
(b) $\frac{4(x^{-1})^{-3}}{4^{-2}(x^{-1})^{-1}}=4^3x^2=64x^2$
Work Step by Step
(a) $\frac{(5a)^{-2}}{(5a)^2}=\frac{1}{(5a)^2(5a)^2}=\frac{1}{(5a)^4}=\frac{1}{625a^4}$
(b) $\frac{4(x^{-1})^{-3}}{4^{-2}(x^{-1})^{-1}}=\frac{4(4)^2x^3}{x}=4^3x^2=64x^2$
