**Riddle**: A young man decides to buy a collector’s baseball card. He pays $60 for it. After a month, the value of the card has increased to $70 and he decides to sell it. But already a few days later he regrets his decision to sell the collector’s item, and he buys it again. Unfortunately he has to pay $80 to get it back, so he loses $10. After a year of owning the baseball card, he finally decides to sell it for $100. What is his overall profit?

This riddle seems very easy at first, but you need to be careful solving it or you might think you have found the answer correct and disappoint when you realize you could not find it. The most important thing you need to be careful is that the riddle asks for the overall profit not net profit. When he buys the card for $60 and sells it for $70, his profit here is $10. Later, he again buys it for $80 and after a while he again sells it for $100, his profit from this sale is $20. Therefore, his overall profit is the addition of his first and last profits and the answer is $30.

The answer is: $30.00. Overall profit, not net profit!