Suppose your uncle is 50 and has a plan to retire at age 70, but his fortune teller told him that he will live for fifty more years. If he would like to have a steady income of $180,000 per year after his retirement and the interest rate will be 8% compounded yearly at that time, how much must he set aside each year till his retirement to be able to achieve his goal, if the interest rate is now 9% compounded yearly? Also, assume that your uncle has a current balance of $60,000.

Please I would appreciate the formulas to derive the answer with a step by step explanation. without the use of excel.