Question 3 5 marks David opens a savings account. The savings account pays interest at a rate of 0.25% per month. At the start of each month he deposits $X into the account. At the end of each month, after interest is added he withdraws $2500 to pay his living expenses. Let Mn be the amount in the savings account after the nth withdrawal. Formulate this as a Difference Equation problem and find the value of X so that the amount in the savings account is $84 000 after the last withdrawal of the fifth year