Let x and y be natural numbers.

True

If $x$ divides $y$, then $\frac{y}{x}$ is a natural number.

$\Rightarrow \quad\left(\frac{y}{x}\right)^{3}$ is also a natural number.

$\Rightarrow \quad \frac{y^{3}}{x^{3}}$ is a natural number.

$\Rightarrow \quad x^{3}$ divides $y^{3}$