please help

A) David wins the lottery, and earns $500000. He wants to deposit this into an account that pays 6% per annum, compounded monthly in order to withdraw a certain amount every month for 20 years. How much can he withdraw every month? B) Candice starts depositing $100 every month into an account with 5% interest per year, compounded bi weekly. Determine how much money she will have after 3 years (future value)