Surds question grade 10 I am a student and need help answering this question. I need a step by step solution.
Simplify:
$ \sqrt {18}$ - $ \sqrt {9}$ 
What I tried:
($ \sqrt {9}$ × $ \sqrt {2}$) - 9
= (3$ \sqrt {2}$ ) - 9
I don't know what to do next.
Thank you and help is appreciated.

this is $$\sqrt{2\cdot 9}-\sqrt{9}=3\sqrt{2}-3$$
