Suppose that David has CZK 440 to spend on milk and breakfast cereals. One cereals pack costs CZK 60. Tesco offers a discount on milk; the discounted price is CZK 10 for one milk bottle. However, one consumer might buy a maximum of 10 bottles for the discounted price. If David buys more, he pays an undiscounted price CZK 20 per bottle. Suppose that David buys 12 bottles of milk. How many cereal packs could he afford to buy then?