First, let's simplify the expression:

18! - 1717! - 1616!
= 17!(18 - 17 - 16)
= 17!(18 - 33)
= 17!(-15)

Next, let's simplify the denominator:

17! - 16!
= 16!(17 - 1)
= 16! * 16

Now, let's divide the two simplified expressions:

(17!(-15)) / (16! * 16)
= -15/16