A money-lender borrows money at 4% per annum and pays the interest at the end of the year. He lends it at 6% per annum compound interest compounded half-yearly and receives the interest at the end of the year. In this way, he gains Rs 104.50 a year. The amount of money he borrows, is (a) Rs 4500        (b) Rs 5000       (c) Rs 5500         (d) Rs 6000