Suppose that each year a phone company loses 2% of its cell phone subscribers due to poor customer service, and that this year the company has 400,000 cell phone subscribers. By using promotional give-aways, the company is able to gain 5,000 new cell phone subscribers each year.

Rather than improve their customer service, the company decides to increase the number of their promotional give-aways.

How do I find out how many customers the company needs to gain each year through promotional give-aways in order to remain at a level of 400,000 cell phone subscribers in the long term?