For this case, we have a function of the form:
![y = A * (b) ^ t](https://img.qammunity.org/2019/formulas/mathematics/middle-school/uqbwc0pho3zmo3j0zi1jldjki8tpv4827r.png)
Where,
A: initial amount
b: decrease rate
t: time in years
Then you have the following inequality:
Answer:
An inequality that can be used to determine after how many years, t, will change the tax status of cities is:
![9400 * (0,857) ^ t \ \textless \ 6000](https://img.qammunity.org/2019/formulas/mathematics/middle-school/b7qmigdpclx3mnrqu9xbn7b5mqt9h89vty.png)