What four weights can be used to balance from 1 to 30 pounds?

Find the value of "a" by solving the maths equation in the picture below:

The dirtier I get, the whiter I look. Who am I?

I speak without a mouth, and hear without ears. I have no-body, but I come alive with the wind. What am I?

What has six faces, but does not wear makeup, has twenty-one eyes, but cannot see?

What Does this text mean:

important=important

In the figure that has been attached to this question, each digit represents a digit. The similar letters carry the same integer value. Can you expose the original digits?

How will you measure 15 minutes using two hourglasses of 7 minutes and 11 minutes respectively?

A B C D E F G H

These are the letters given to you. Now you have to find out the letter that comes two to the right of the letter which is immediately to the left of the letter that comes three to the right of the letter that comes midway between the letter two to the left of the letter C and the letter immediately to the right of the letter F.

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?