What does this Rebus Picture mean?

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?

What is black when you buy it, red when you use it, and gray when you throw it away?

How many letters are in the alphabet?

Find the next number in the sequence

5 12 24 36 ?

Replace the question mark with the correct number, given the pair of numbers exhibits a similar relationship?

? : 3839 :: 11 : 1209

What goes up but never comes down?

What happened when the wheel was invented?

An old Woman left INR 33,333 to be divided equally among two fathers and two sons and each was to receive INR 11,111.
How was this possible?

What is the last thing you take off before bed?