There are 10 people to be seated in a row.

Person A and Person B must be seated next to each other.

Person C and Person D must NOT be seated next to each other.

How many arrangements are possible?

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- Sep 14th 2010, 05:00 PMstumped765permutation with restrictions
There are 10 people to be seated in a row.

Person A and Person B must be seated next to each other.

Person C and Person D must NOT be seated next to each other.

How many arrangements are possible? - Sep 14th 2010, 05:03 PMundefined
We can deal with the first restriction by considering A and B as a single person, but with two different versions (AB and BA), thus with just that restriction it would be 2 * 9!.

For the second restriction you can think similarly and start with all permutations, then subtract out those that have C and D next to each other. Can you complete it?