Calculate the level annual income retained by 'A'.?

Four years ago 'A' lent $12,000 to 'B'. The loan was repayable by level annual installments of capital over 12 years and interest was payable annually in arrear at 9% per annum. 'A' retained part of each payment of capital and interest to provide himself with a level annual income and the balance of each payment was sufficient when invested at 7% per annum to replace his original capital at the end of 12 years.
Immediately after the fourth repayment 'B' wishes to change the repayments basis to level annual installments of capital and interest. 'A' will agree to this provided the amount of the level installment of capital and interest payable by 'B' under the revised arrangement is such that he is able to retain the same level of annual income and still replace his capital by adding the balance of each payment to his existing investment at 7% per annum.

You are taking a significant risk when you post homework questions here, as you have no idea whether anyone who answers is academically gifted or not (i.e. a person can be very successful in world of investing but still not be able to answer finance or economics questions correctly). Not to mention the fact that you have a teacher, classmates, and textbook that are more familiar with material you are studying and would be better qualified to help you arrive at correct answer.