A group of investors decides to invest RM500,000 in the stocks of three companies. Company D sells for RM60 a share and has a growth of 16% per year. Company E sells for RM80 per share and has a growth of 12% per year. Company F sells for RM30 a share and has a growth of 9% per year. The group plans to buy four times as many shares of company F as of company E. If the groups goal is 13.68% growth per year, how many shares of each stock should the investors buy? [Solve this question by the method of inverse]