Answer
A combination is a selection of r items from n items where
* the group of r items is selected from the same set of n items,
* no item is used (selected) more than once, and
* the order of the items is not important.
Work Step by Step
A combination is a selection of r items from n items where
* the group of r items is selected from the same set of n items,
* no item is used (selected) more than once, and
* the order of the items is not important.