The answer is 16/25, but I don't know how to get to it

[safe flame]

If four couples of boyfriends and girlfriends are randomly arranged in a line, determine the probability that none of the couples stay together

[cerulean onyx]

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[karmic quail]

i don't think it's 16/25, you can know that because (naming each couple AA, BB, CC, DD) there are 8!/(2^4) permutations of AABBCCDD which is 2520 which 25 does not divide