A woman has nine close friends. (a) In how many ways can she invite six of these to dinner? (b) Repeat (a) if two of her friends are divorced (from each other) and will not attend together. (c) Repeat (a) if the friends consist of three single people and three married couples and, if a husband or wife is invited, the spouse must be invited too.
+934 a. 9 C 6= 84. This is the easiest one.....This is how many ways she can invite six of the nine friends with no restrictions.
