Answer with formula

4) Alex, an engineering graduate, who is planning for early retirement 20 years from now. He believes that he will need $1,000,000 in year 20. He already has $100,000 in his investment account. How much will he has to invest each year for of the following 20 years if the account grows at a rate of 10% per year? 5) 20 years later, Alex is has $1,000,000 in his investment account. He plans to spend $200,000 each year from his account. How many years would it take before his account is depleted? Use i = 10% per year