Amit, Priya, and Ravi enter into a partnership. Amit invests Tk. 40 lakh initially and adds Tk. 20 lakh after 2 years. Priya invests Tk. 50 lakh initially and withdraws Tk. 15 lakh after 1 year. Ravi invests Tk. 60 lakh throughout. In what ratio should the profit be divided at the end of 4 years?