There are no restrictions. Simplify your answer to one final number. For b and c Do not simplify your answers. Leave in combinatorics form. b. Two of my friends are married so if I invite one, I have to invite the other. c. Two of my friends do not like each other so if invite one, I cannot invite the other

The correct answer is : I have to invite 8 friends

Explanation:

Two are married so a friend cannot be invited without the other one. Therefore, I'm going to be invited to a distinct friend instead of those two. The total number of available people is 10. And can be invited only 8 friends now because it will avoid any possible confrontation between the ones who don't like each other.

n=10

r=8