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## Homework Statement

7 distinct flags are hoisted in a post. Find the number of ways of arranging them if

2 of the flags must be separated. (The answer is 3600)

## Homework Equations

Permutation: n!

Circular Permutation: (n-1)!

## The Attempt at a Solution

1: Flag 1, 2: Flag 2:

The arrangements should be:

1 X 2 X X X X

X 1 X 2 X X X ...

2 X 1 X X X X

X 2 X 1 X X X ...

1 X X 2 X X X

X 1 X X 2 X X ...

2 X X 1 X X X

X 2 X X 1 X X ...

......

I don't know how to calculate the solution provided.

Can anyone tell me how to solve the above problem?

Thank you very much!