On January 1st Kendra puts $100 into her bank account. On the first of each month after that she deposits an additional $100. Unfortunately, during the middle of the month she always has to withdraw 75% of her money to pay bills.
(a) How much money is in Kendra's account at the end of March?
(b) How much money is in Kendra's account at the end of n months? Write your answer in closed form.