Without any restrictions there are possible teams
There are possible teams that include both Bob and Joe.
Would the difference be the answer to the question?
you have 18 people to choose from and you are making an 11 person soccer team....how many ways are there to choose a team so that Bob and Joe are not on the team together
there are 18 C 11 ways total and then is it 17 C 11 if bob doesnt play and then multiply it by two for if joe doesnt play
so 2(17 C 11)
is that correct?
The case where both of them are in the team is the only one we want to avoid.
I hope it helps you understand :x