Please solve without excel using the appropriate equations.

John borrows X for 12 years at an annual effective interest rate of 7%, to be repaid with payments at the end of each year. The amount of the first payment is 2,140. In each subsequent year, the payment amount is increased by g% over the payment amount during the previous year, where g is a positive integer between 6 and 10. The outstanding loan balance at the end of the 5th year is 19,635.72. Calculate the principal repaid in the second payment.