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 4 years, after which declining production will decrease revenue by 10% each year. If the aquifer will be totally depleted in 20 years. What is the present worth of the desalting option at an interest rate of 6% per year