The city of san antonio is considering various options for providing water in its 50-year plan, including desalting. one brackish aquifer is expected to yield desalted water that will generate revenue of $4.1 million per year for the first 6 years, after which less production will decrease revenue by 10% per year each year. if the aquifer will be totally depleted in 22 years, what is the present worth of the desalting option revenue at an interest rate of 6% per year?