1. A 12-year loan of 14,000 is to be repaid with payments at the end of each year consisting of interest on the loan and a sinking fund deposit. Interest on the loan is charged at a 10.5% annual effective rate. The sinking fund's annual effective interest rate is 7%. However, beginning in year 7, the annual effective interest rate on the sinking fund drops to 4%. As a result, the annual payment to the sinking fund is then increased by X. Calculate X.