On May 01 of each year, a person pays 20,000 dinars capitalized at 7%. After making 10 payments, she leaves the amount acquired in the bank for 5 years at the rate of 8%. At the end of the 5 years, on May 1 of each year, it makes 10 withdrawals of 20,000 dinars each (annual interest rate = 7%).

Calculate the available balance immediately after the last withdrawal.

What constant sum would have had to be invested for this balance to be zero?