Total ways to arrange the 7 letters: 7! / (2! x 2!) = 1260
Ways to have an N at each end: N _ _ _ _ _ N
There are 5 other letters in the middle, and two of them repeat (U), so the middle 5 are found by 5! / 2! = 60
Now, here is where I am unsure what to do. Since the N's are identical, do...