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Just solved under this link
https://www.algebra.com/algebra/homework/Permutations/Permutations.faq.question.1116314.html
https://www.algebra.com/algebra/homework/Permutations/Permutations.faq.question.1116314.html
Please do not post duplicates.
EITHER your problem is formulated clearly and correctly - and then it will be solved after your first submitting;
OR it is not formulated clearly and correctly - and then nothing (even posting duplicates) will help.