Replace the question mark with the number below given a simple math problem.

If an electric train is travelling south, then which way is the smoke going?

Find the hidden tiger in the given optical illusion ?

A word I know,
Six letters contain,
Subtract just one,
And twelve is what remains.

Three cars are driving on a track that forms a perfect circle and is wide enough that multiple cars can pass anytime. The car that is leading in the race right now is driving at 55 MPH and the car that is trailing at the last is going at 45 MPH. The car that is in the middle is somewhere between these two speeds.
Right now, you can assume that there is a distance of x miles between the leading car and the middle car and x miles between the middle car and the last car and also, x is not equal to 0 or 1.
The cars maintain their speed till the leading car catches up with the last car and then every car stops. In this scenario, do you think of any point when the distance between any two pairs will again be x miles i.e. the pairs will be x distance apart at the same time ?

I have no life, but I can die. What am I?

He digs out tiny caves and stores gold and silver in them. He also built bridges of silver and made crowns of gold. They are the smallest you could imagine. Sooner or later everybody needs his help, yet many people are afraid to let him help them. Who is he?

Can you find a number that lies one third of the distance between 1/3 and 2/3?

Solve the counting riddle by identifying the number of triangles in the given picture.

You walk into a room that contains a match, a kerosene lamp, a candle and a fireplace. What would you light first?