The purchaser of a tractor paid P10,000 cash and agreed to pay P3000 at the end of 6 months for 10 years. He failed to make the first 5 payments of P3000 each. At the end of 3 years he desires to pay the tractor by a single payment which will cancel both his accumulated liabilities and his future liabilities. What must he pay if money is worth 6% per annum compounded semi-annually?