Answer:
190 possibilities.
Step-by-step explanation:
The problem is called 20 choose 2, given by the formula for combinations
C(20,2) = 20! / (2! (20-2)!) = 190
alternatively, we can reason it this way:
there are 20 choices to choose a captain and 19 choices for an alternate captain for a total of 380 ways.
However, there are 20 choices to choose an alternate captain and 19 choices for a captain for a total of 380 ways.
Since we are essentially double counting every choice of the posts, we need to divide 380 by 2 to get 190 ways.
