Answer
(a) $320x^{2}y^{3}$
(b) $\frac{1}{yz^{3}}$
(c) $\frac{a^{6}}{b^{10}}$
Work Step by Step
(a) $(5x^{-4}y^{3})(8x^{3})^{2}=5x^{-4}y^{3} 8^{2}x^{3\cdot 2}=5*8^{2}x^{-4+6}y^{3}=320x^{2}y^{3}$
(b) $\frac{y^{-2}z^{-3}}{y^{-1}}=\frac{y}{y^{2}z^3}=\frac{1}{yz^{3}}$
(c) $(\frac{a^{3}b^{-2}}{b^{3}})^{2}=\frac{a^{6}b^{-4}}{b^{6}}=\frac{a^6}{b^6b^4}=\frac{a^{6}}{b^{10}}$