it's easier to find the number that do have them next to each other. In that case, there are effectively 8 cards. 7 of the other colors, and one pink-green card.
So, there are 8! ways to arrange the "8" cards.
Then, you can swap the pink and green, so the total is 2*8!
Now just subtract that from the original 9! arrangements to get your answer.
9 cards each of different colors include a pink card and a green card.
1.How many different arrangements do not have the pink card next to the green card?
1 answer