Please show work. Answer will be 2800.

During the first 4 years, interest is credited using a simple interest of 5% per year. After 4 years, interest is credited at a force of interest 0.2 4 1 0.2t The following are numerically equal (i) The value at time t = 4 of payments of 1000 at time t 2 and 400 at time t = 7 (ii) The present value at time t = 0 of a payment of X at time t= 10 1 Calculate X