Create two different situations: one in which you use combinations and one in which you use permutations

Question

please help me with this question or give me some sites too look at, I don't understand.

Answer 1

Permutation: the order matters
e.g. In how many was can 8runners finish first, second , and third
number of ways = 8*7*6 = 336 or 8!/5!

combination:
A teacher wants to choose 3 students from 8 to form a clean up crew. The order in which the 3 students are chosen does not matter.
number of ways = 8!/(3!5!) = 56

google "permutations vs combinations"

Answer 2

http://www.mathsisfun.com/combinatorics/combinations-permutations.html

Answer 3

Thank you very much too the both of you!!! Now I understand!!!