Maintenance money for a new building at a college is being solicited from potential alumni donors. You would like to make a donation to cover all future expected maintenance costs of the building. These maintenance costs are expected to be $48,000 per year for the first five years, $60,000 per year for each of years 6 through 10, and $72,000 annually after that (toward infinity under the assumption that the building has an indefinite service life). If the money is placed in an account that will pay 15% annual interest, how large should your gift be?