Yup, combinations problems when there’s something extra to worry about. Not just the old , but something more.
I looked at the first example in the following file, but we completed a simpler version of the second problem. It’ll help you to solve some of the homework, though: Combinations with Restrictions
And here’s the homework: Page 280 #9, 11, 12, 13. You can also do 15 if you like :)