Chapter 5 - Section 5.4 - Multiplying Polynomials - Exercise Set - Page 289: 51

$-24a^2b^{3}+40a^2b^{2}-160a^2b$

\text{ Using the Distributive Property, the given expression is equivalent to }\\ \begin{align*} & -8a^2b(3b^2-5b+20) \\\\&= -24a^2b^{1+2}+40a^2b^{1+1}-160a^2b \\\\&= -24a^2b^{3}+40a^2b^{2}-160a^2b .\end{align*}