.
The number of distinguishable arrangements is
=
= 1260 in this case.
In the denominator, the factors 4!, 2! and 3! serve to account for multiplicities of the identical items / flags.
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Just a reminder for visitors (!)
When I solve a problem for you, I expect to get your "THANKS" back.
It is the simple and standard way to let me know that you are an educated person.
Otherwise, I will think that I work for idiots.