A loan is repaid with payments made at end of each month. The first payments is $3000, with each successive payment being $20 less than the previous and a final payment at month 48 of $2060 (i.e., payments of 3000, 2980, 2960, 2940, . . . , 2060 when t is 1, 2, 3, 4, . . . , 48). The interest rate on the loan is nominal annual rate of 7.2%, compounded monthly. What is the balance on the loan after the 18th payment?