Lyle pays a loan by means of two payments. The first repayment of R13 000 is made after four years. The second and final repayment amounting to R5 000 is made three years later. The interest rate during the first four years is 9% per annum compounded semi-annually. For the remaining three years, the interest rate changes to 12% per annum compounded monthly. How much did Lyle originally borrow?