Who among the following is the author of the book

What will be the cost of painting the four walls of a room if the rate of painting is Rs. 20 per square metre?

What is the value of number x ?

I. The HCF of x and 16 is 8.

In each of the following questions, read the given statement and compare the Quantity I and Quantity II on its basis.  

Find the Income of Suleiman?

Statement I: Suleiman's income exceeds Salman's by Rs. 8000, and Salman's savings amount to Rs. 15,000.

What is the capacity of a cylindrical tank?

I. The radius of the base is half of its height, which is 14metres.

What is the age of Kunal?

Statement I - Four years ago, the age of Kunal was three-fourth his present age.

What is the length of the train?

How much time will train A take to cross a platform of length 400 m?

I. The train A crosses another train B in 40 seconds.

What is Jackson’s annual income?

There are 7 people in a group. Average age of the group decreases by 5 when two more people join the group. Find the average age of the new group.