a)
192^{\frac{1}{6}}=(64\cdot 3)^{\frac{1}{6}}=64^{\frac{1}{6}}\cdot 3^{\frac{1}{6}}=(2^6)^{\frac{1}{6}}\cdot \sqrt[6]{3}=2^{\not6\cdot \frac{1}{\not6}}\cdot \sqrt[6]{3}=2\sqrt[6]{3}
b)
{(\frac{1}{27})^{-\frac{2}{3}}=(27^{-1})^{-\frac{2}{3}}=27^{(-1)\cdot (-\frac{2}{3})}=27^{\frac{2}{3}}=(3^3)^{\frac{2}{3}}=3^{\not3\cdot \frac{2}{\not3}}=3^2=9}