A soda company sends bottles of their soda to stores around the city in old and new vans. An old van can take 100 soda bottles while a new van can take 80 soda bottles. An old van produces 50 units of pollution while a new van only produces 30 units of pollution. The company needs to send at least 5000 bottles. In addition, at most 30 new vans can be used. How many of each van should be used to minimize the total amount of pollution produced?