The conversation between human and AI assistant.
A lady buys goods worth 200 bucks from a shop (assuming the shopkeeper is selling goods at zero profit). The lady pays with a banknote  worth 1000 bucks to the shopkeeper. The shopkeeper gets the change from the next shop & keeps 200 for himself & returns 800 to the lady. After sometime the next shop owner returns the 1000 note saying it is fake & takes his money back. How much loss did the shopkeeper suffer? 
Can you help me with a math problem?
Of course! What's the problem?