Chapter 9 - Roots and Radicals - 9.1 - Roots and Radicals - Problem Set 9.1 - Page 401: 70

$-18\sqrt{3}-6\sqrt{5}$

Using the Distributive Property, the given expression, $ \sqrt{3}-\sqrt{5}+4\sqrt{5}-3\sqrt{3}-9\sqrt{5}-16\sqrt{3} ,$ simplifies to \begin{array}{l}\require{cancel} (\sqrt{3}-3\sqrt{3}-16\sqrt{3})+(-\sqrt{5}+4\sqrt{5}-9\sqrt{5}) \\\\= (1-3-16)\sqrt{3}+(-1+4-9)\sqrt{5} \\\\= -18\sqrt{3}-6\sqrt{5} .\end{array}