## Intermediate Algebra for College Students (7th Edition)

The answer is $12\sqrt {5}$.
The given expression is $8\sqrt {45}+2\sqrt 5-7\sqrt {20}$ Factor the number under root. =$8\sqrt {5\cdot 3 \cdot 3}+2\sqrt 5-7\sqrt {5\cdot 2\cdot 2}$ Simplify. =$8\cdot 3\sqrt {5}+2\sqrt 5-7\cdot 2\sqrt {5}$ =$24\sqrt {5}+2\sqrt 5-14\sqrt {5}$ =$26\sqrt {5}-14\sqrt {5}$ =$12\sqrt {5}$.