31to42 pls someone me whats the ans.

I will tell you how to solve the first one, and then you have to try to do the rest of them by yourself. :) because doing math is also a process of learning. 

31. \sqrt{6}(\sqrt{2}+\sqrt{6})
    =\sqrt{12}+6                           distribute and simplify
    =2\sqrt{3}+6                           take a 2 out, and you get the answer.

The answer to your question is b