# How do you rationalize the denominator (2sqrt108)/(sqrt180y)?

$\frac{2 \sqrt{108}}{\sqrt{108} y}$
$= \frac{2 \cdot \cancel{\sqrt{108}}}{y \cdot \cancel{\sqrt{108}}}$
$= \frac{2}{y}$ which has a rational denominator as long as $y \epsilon \mathbb{Q}$