X and Y are partners in a business. They share capital, profits and losses in the ratio 2 : 1. At the beginning of the year, the combined capital of the firm stood at Rs. 24,00,000. They both agreed to reconstitute their firm's capital composition and the terms are as follows. Mr. X is to divest Rs. 9,00,000 from his investment in three equal installments at the end of quarters 1, 2 and 3 of the year. Accordingly, Mr. Y is to bring the required amount at the same time, so as to make their capital ratio 1 : 2, considering X's capital as base. If the profit earned for the period is Rs. 9,00,000, then calculate the return on investment of the firm for the financial year.