Answer
$-y\sqrt[3]{2x}$
Work Step by Step
Simplify each radicand to obtain
$\sqrt[3]{(27y^3)(2x)}-y\sqrt[3]{64(2x)}
\\=\sqrt[3]{(3y)^3(2x)}-y\sqrt[3]{4^3(2x)}
\\=3y\sqrt[3]{2x} - 4y\sqrt [3]{2x}.$
RECALL:
The distributive property states that for any real numbers a, b, and c,
$ac + bc = (a+b)c
\\ac - bc = (a-b)c.$
Use the distributive to obtain
$(3y-4y)\sqrt[3]{2x}
\\=-y\sqrt[3]{2x}.$