: An amortized loan is repaid with annual payments which start at $400 at the end of the first year and increase by $45 each year until a payment of $1480 is made after which they cease. If interest is 4% effective, find the amount of principal in the 14th payment. The answer is $530.18, Please show all work and steps. Someone had answered this question before on Chegg, and mentioned it is impossible to solve because there is no 14th payment, because by the 3rd / 4th year, the payment is close to ceasing. Please answer if you see how to arrive at the solution of $530.18, I'd greatly appreciate it.