Because n objects can be arranged in a row in ways.

Just imagine yourself placing these 5 people on 5 the seats of a row: You first place Martha in the middle (no alternative choice is possible here). The only choice that you have is how to arrange the 4 friends on the remaining 4 seats. And in how many ways can that be done? (Note that it doesn't matter whether the 4 remaining seats are next to each other or not.)In how many of those ways is Martha sitting in the middle?

I need help with setting up the problem.

If you can help, I really appreciate it!