H9.

A 12-year loan is repaid with annual payments at the end of each year. For the first four years, each payment is X; for the next four years, each payment is 3X; for the final four years each payment is 2X. The amount of interest due in the fifth payment is twice as much as the interest due in the 9th payment. Find i, the (non-zero) annual effective interest rate, rounded to two decimal places after converting to a percentage.

Please solve using steps and definitions, not Excel spread sheet.