Question 1
An may buy at most two items, and may choose the same kind twice. A ruler costs 3,000 đồng, a pencil 4,000 đồng, and a ball 7,000 đồng. An has only 1,000-đồng and 5,000-đồng banknotes and pays the exact price. Which of the following cannot be the number of banknotes An pays?
