Chapter 5 - Number Theory and the Real Number System - 5.4 The Irrational Numbers - Exercise Set 5.4 - Page 299: 97

$\textbf{does not make sense}$ The way the radicals were simplified was wrong. (refer to the explanation below)

The statement $\textbf{does not make sense}$ because the radicals were not simplified correctly.. The correct simplification is: \begin{align*} \sqrt{20} + \sqrt{75}&=\sqrt{4(5)} + \sqrt{25(3)}\\ &=2\sqrt5+5\sqrt3 \end{align*}