Chapter 7 - Section 7.5 - Multiplying with More Than One Term and Rationalizing Denominators - Exercise Set - Page 551: 107

$-2\sqrt[3]{25}$

Rationalize $\displaystyle \frac{15}{ \sqrt[3]{5}}$ $\displaystyle \frac{15}{ \sqrt[3]{5}}\color{red}{ \cdot\frac{ \sqrt[3]{5^{2}}}{\sqrt[3]{5^{2}}} }=\frac{15\sqrt[3]{25}}{\sqrt[3]{5^{3}}}=\frac{15\sqrt[3]{25}}{5}=3\sqrt[3]{25}$ $3\sqrt[3]{25}-5\sqrt[3]{25}=-2\sqrt[3]{25}$