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## Homework Statement

a) if jack has 10 friends, in how many ways can he invite 5 of them to dinner.

b) suppose 2 friends don't like each other, and if one is invited, the other can't come.

c) what if 2 of the friends are married and if they invite that friend, the spouse must come.

## Homework Equations

Rule of products

## The Attempt at a Solution

a) I get 10*9*8*7*6 = 30240 ways.

b) I simply subtract one friend initially to get 9*8*7*6*4 = 15120 ways

c) I subtract to 8 friends because their spouses fill the spots of the other 2.

8*7*6*5*4 = 6720 ways

I'm unsure if I'm misinterpreting the question. My method goes by the order in which they are invited..any help is much appreciated