You want to buy a ring for your mum. There are many rings but you don’t know the price. You have 3 ₤. Ask for the price of the silver ring with the black stone. It costs 13 ₤ - too expensive!! You ask for cheaper (billigere) ones. The shop assistant shows you some. They’re made of plastics (sie sind aus Plastik). You take a black one which costs 2,75 ₤.