The function f(n) = 500(.85) n
represents the amount of money left in jennifer's bank account after in years. at what rate is the amount of money in her account changing increasing or decreasing and at what rate

You're really seeing this problem in elementary school?  Wow.  

The function f(n) = 500(.85) n
Represents the amount of money left in Jennifer's bank account after in years. At what rate is the amount of money in her account changing increasing or decreasing and at what rate

This problem involves exponentiation:  f(n) = 500 (0.85)^n, where the 
symbol " ^ " denotes exponentiation.  f(n) = 500 (0.85) n is all multiplication and thus is not correct.

That 0.85 is the base of an exponential function, and n is the exponent.
Because this base is between 0 and 1, the function f(n) is DECREASING.

What do you think the rate is?

The sum is 2,160, no problem