Use only one mathematical symbol and all numbers (0-9) to get a sum of 99

A boy was at a carnival and went to a booth where a man said to the boy, "If I write your exact weight on this piece of paper then you have to give me $50, but if I cannot, I will pay you $50." The boy looked around and saw no scale so he agrees, thinking no matter what the carny writes he'll just say he weighs more or less. In the end the boy ended up paying the man $50. How did the man win the bet?

A train full of passengers goes through a tunnel. When the train comes out from the other end, there is no single person on the train.

How did it happen?

A woman lives in a Tall building thirty-six floors high and served by several elevators which stop at each floor going up and down. Each morning she leaves her apartment and goes to one of the elevators. Whichever one she takes is three times more likely to be going up than down. Why?

Which wheel of car does not rotate when you turn your car right?

Find the number of squares in the below picture

What animal walks on four legs in the morning, two legs during the day, and three legs in the evening?

Oedipus, the king of Thebes, figured out the answer to the riddle:

A man and his wife were doing missionary work near the city of Nairobi in the country of Kenya in eastern Africa. Their housing had not yet been completed, so the man, the woman, and their six year old daughter were spending a few nights in the jungle in three small pup tents. During their third night there, the woman was awakened by the call of a hyena passing by, so she got out of her tent to see if her young daughter had been frightened by the noise. As she peered into her daughter's tent she was surprised to see the dark figures of lion, a panther, and a cheetah which were curled up next to her daughter. Seeing her daughter was asleep and unharmed, the woman slowly and quietly withdrew from the tent, and simply returned to her own tent and went back to bed. How could this child's mother leave her daughter in such a dangerous situation, and simply ignore what she had just witnessed without intervening in some way? How can such emotional coldness ever be explained; or is there something here we are missing?

What number when divided in half becomes zero?

A man is walking down a road with a basket of eggs. As he
is walking he meets someone who buys one-half of his eggs
plus one-half of an egg.
He walks a little further and meets another person who buys
one-half of his eggs plus one-half of an egg.
After proceeding further he meets another person who buys
one-half of his eggs plus one half an egg. At this point, he
has sold all of his eggs, and he never broke an egg.
How many eggs did the man have to start with?