An agent wishes to purchase a number of chairs and tables. He has only Rs. 12000 to invest and has space at most for 28 items. A chair costs him Rs. 480 and a table costs Rs. 300. His expectation is that he can sell a chair at a profit of Rs. 200 and a table at a profit of Rs. 150. Assuming that he can sell all the items that he can buy, how should he invest his money in order to maximize his profit?