do not use excel, please.

A loan of $20,000 is being paid by installments of $1,000 at the end of each six-month period and a smaller final payment made half a year after the last regular payment. The interest rate for the loan is a nominal interest rate of 6% convertible semiannually. Find the outstanding loan balance when the bor- rower has made payments equal to 75% of the original amount of the loan