The order of the members in the row matters, so this is a permutation. Now, we solve:
Slots in the row:
_ _ _ _
In the first slot of the row, we can have 1 of 15 members:
15 _ _ _
In the second, we can have 14, and then 13 and so on:
15 14 13 12
Now, we multiply all these numbers:
15 x 14 x 13 x 12 = 32,760 possible arrangements
