Spot what is wrong here in below Picture?

Find out the missing number in the picture attached:

John drives to his office at 20km/hr. After reaching the office, he realizes that today is a holiday. He went back at an average speed of 30km/hr. Discounting the time spent in the stoppage what was the average speed of his journey?

Can you place six X (crosses) in below board without making three in a row in any way ?

You are on a Boat in the mid of a river. You have two cigarettes with you. One of these two you have to light, how will you light the cigarette?

Quickly Solve this riddle

7 - 4 + 3 * 0 + 1 = ?

If eleven plus two equals one, what does nine plus five equal?

What always comes into a house through the keyhole?

Count the number of triangles in the given picture.

You can hear me, but you can't touch or see me.

What am I?