7. A person is planning for his retired life. He has 10 more years of service. He would like to deposit 20% of his salary, which is 4,000 US. Dollars at the end of the first year, and thereafter he wishes to deposit the amount with an annual increase of Rs. 500 for the next 9 years with an interest rate of 15%. Find the total amount at the end of the 10th year of the above series.