Smart deal!

 
 
A Grandpa and a Grandson Smith was seating next to each other in a Bus. 

Grandpa said to Smith lets play a game.

I will ask you a question and if you didn't get the answer, you will pay me $100, and if u ask me a question and I didn’t get the answer,

 I will pay you $10000. The Grandpa started: What is the distance from the Earth to Jupiter? Smith doesn't say a word, he reaches his pocket and pulled out a $50 and gave him. Now it's Smith turn to ask. 

He said: what goes up in the hill with 5 legs and comes down with 7 legs? 

The Grandpa Thought for a long time, searches the internet, and asked all his smart friends but couldn't get the answer. He reaches his pocket and pulled out a $10000 and gave it Smith. Grandpa got mad and asked Smith: well, what the hell goes up the hill with 5 legs and comes down with 7 legs?. Smith just deep his hand into his pocket and gave Grandpa $100 and said: I don't know also.