# How do you add and subtract radicals like: sqrt(6/3) -sqrt(9/3)?

The root operator is prior to addition. So we need to calculate each square root operation independently. We cannot combine $\frac{6}{3}$ and $\frac{9}{3}$.
$\sqrt{\frac{6}{3}} - \sqrt{\frac{9}{3}} = \sqrt{2} - \sqrt{3}$
So the answer is $\sqrt{2} - \sqrt{3}$.