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

My cousin lives in one story house in Antarctica. His house is made the of-of sandstone. what is the color of stairs?

If in a car race, the man who came two places in front of the last man finished one ahead of the man who came fifth, how many contestants were there?

A container contains 100 eggs. They can be either fresh or rotten. What is sure is the fact that there is at least one fresh egg in that container.

If you are asked to pick two eggs randomly from the container, at least one of them will be rotten.

Can you calculate how many eggs in that container are fresh?

What goes through cities and fields, but never moves?

There was once a college that offered a class on probability applied to the real world. The class was relatively easy, but there was a catch. There were no homework assignments or tests, but there was a final exam that would have only one question on it. When everyone received the test paper it was a blank sheet of paper with a solitary question on it: 'What is the risk?'.Most students were able to pass, but only one student received 100% for the class! Even stranger was that he only wrote down one word!
What did he write?

Can you find the missing number in the third row?
35 20 14
27 12 18
5 2 ?

How is a fly different from a mosquito?

You Throw The Outside, Cook The Inside
Eat The Outside, Throw The Inside.

What Is It?

What does an Island and the letter T have in common?