is there a post/discussion/site to help me with combinations? I am really weak at combinations (and probability)... specially when they are combined. Combination/permutation/probability questions are pretty much the only type of question I have gotten wrong on my last 4 practice test, and are the ones keeping me out of the 700 range.

I just have a lot of trouble with the set up and understanding which type of question it is. I have already read many things on the net, and this site is my last hope!

Any guides/links/files/books/problems to help explain this to me? Whoever helps me the most I will gladly donate $10 via paypal for your time.