Simplifying square roots?

I am having a lot of trouble in my math class.

I go to school online and am stuck on a particular unit, and my book isn't doing much to helping.

I normally don't do this, but I am really at a loss and I want to graduate on time. Thanks!

7.) 3 square root of 2 - 2 square root of 3

8.) 2 square root of 3 + square root of 27 - square root of 1 / 3

9.) square root of 3 ( square root of 6 - 2 square root of 3 )

10.) square root of 1 / 2 x ( square root of 8 + square root of 2 )

11.) square root of 18 - square root of 3 / square root of 6

12.) square root of a + square root of b / square root of a - square root of b

13.) square root of 5 + 1 / square root of 5 - 1