Answer
(a) $\frac{4}{5}$
(b) $\frac{9}{10}$
Work Step by Step
(a) $\sqrt[3] {\frac{64}{125}}=\frac{\sqrt[3] {64}}{\sqrt[3] {125}}=\frac{\sqrt[3] {4^3}}{\sqrt[3] {5^3}}=\frac{4}{5}$
(b) $\sqrt {\frac{81}{100}}=\frac{\sqrt {81}}{\sqrt {100}}=\frac{\sqrt {9^2}}{\sqrt {10^2}}=\frac{9}{10}$
