Here's the question you clicked on:
raleung2
A science class must choose 5 out of 16 science fair projects to advance to the county competition. How many different groups of projects could be selected?
16 chances on the first pick 15 on the second pick 14, then 13 then 12 ... then its full
but, that counts abc as different from bca
to weed out the repeats since groups dont care about order we can divide that by 5!
you should have material that explains the notation better than I can
ok. then whats the final anseer?
\[\dbinom{16}{5}\] but that doesn't answer the question, it just restates it in notation