The function is y=21500(1-0.12)ˣ, and the value after 6 years would be 9985.
The general form of the function is y=a×bˣ, where a is the initial value, b is the rate of increase (in this case, decrease) + 1, and x is the number of years.
Substituting 6 for x, we have:
y=21500(1-0.12)⁶=21500(0.88)⁶=9984.69≈9985.