@ash2326 how u do this?

in how many ways can nine people be lined up for a photograph if clark and billy must not stand next to each other

Question

@ash2326  how u do this?

in how many ways can nine people be lined up for a photograph if clark and billy must not stand next to each other

kropot72 · Answer

If there are no restrictions on arrangements there are 9! permutations of the nine people.
There are 16 ways of having Clark and Billy standing next to each other. Each of these 16 ways can be combined with one of the 7! permutaions of the remaining people.

Therefore the number of ways with the restriction = 9! - (16 * 7!)

directrix · Answer

Another interpretation of the problem at: http://openstudy.com/study#/updates/512d9d0ae4b02acc415e65ab