A dealer wishes to purchase a number of fans and sewing machines. He has only $?\, 5760$ to invest and has space for at most $20$ items. A fan and sewing machine cost $?\, 360$ and $? \,240$ respectively. He can sell a fan at a profit of $?\,22$ and sewing machine at a profit of $? \,18$. Assuming that he can sell whatever he buys, how many fans and sewing machines respectively he sell in order to maximize his profit?