Tony has two fish. Every year, his parents buy him two more, but one of them dies. How many fish will he have in five years? Let's think first. Chain of thought:
Each year Tony has one more fish than before because 2 - 1 = 1. In five years, he will have 5 more fish because 5 x 1 = 5. In five years he will have 7 fish because 2 + 5 = 7.
Therefore, the answer is 7.