Mr. Brown has two sons, Sam and Tim. He gives each of them an envelope containing $50 before leaving for work. While he's away, Sam spends his money on video games, while Tim saves his. Their sister, Lisa, secretly takes $20 from Tim's envelope and uses it to buy a gift for her friend. When Mr. Brown returns home, what does he believe about the money he gave his sons, and what is the actual situation?
Respond very briefly.
Mr. Brown believes that each of his sons still has an envelope with $50, as that is what he left them with, and he has no knowledge of the subsequent events that occurred after he left for work. He assumes that Sam and Tim have not spent or altered the amount of money he provided. However, the actual situation is different. Sam has spent his $50 on video games, which means his envelope is now empty. Tim intended to save his money and should have had his full $50, but due to Lisa taking $20 to buy a gift for her friend, Tim's envelope now contains only $30. Mr. Brown is unaware of these transactions, and his belief does not reflect the actual status of the money with his sons.