Answer
$-\sqrt[3]{2 }$
Work Step by Step
We simplify by using the fact that $\sqrt[n]{a}=a^{1/n}$ and then combine the like terms as follows:
$$
5\sqrt[3] 2-2\sqrt[3]{54}=5\sqrt[3] 2-2\sqrt[3]{2\times3^3}
=5\sqrt[3] 2-6\sqrt[3]{2 }\\=(5-6)\sqrt[3]{2 }
=-\sqrt[3]{2 }
.$$
