Show step-by-step solution. Compute manually.

4. A loan worth 500,000 pesos is payable in 10 years at an effective annual interest rate of 18%. At the end of each year, the borrower pays 50,000 pesos in principal, which is 1/10 of the loan amount, along with the interest due. Find a formula for the kth payment P. Then construct an amortization schedule.