The graphs of x = a and y = b intersect at 

What will be the change in the volume of a rectangular solid by increasing its length by 10 percent and decreasing its width by 10 percent?

While purchasing one item costing Rs.400, one has to pay sales tax at 7 % and on another costing Rs. 6400, the sales tax was 9%. The percentage of sales tax one has to pay, taking these items together on an average is: 

Direction: In the following questions two equations numbered I and II are given. You have to solve both the equations and give answer.
(A) x>y
(B) x≥y
(C) x˂y
(D) x≤y
(E) x=y or the relations ship cannot be established

I. 2x+ 3y
II. 4x + 2y=16 

If the sum and difference of two number are 20 and 8 respectively, then the difference of their squares is: 

The area enclosed between the circumferences of two concentric circles is 45π square cm and their radii are in the ratio of 3:2. What is the area off the outer circle?

Direction : What should come in place of the question (?) in the following question.

√(?) + 15² = 235

Find the value of k in $$ {26\over 21}:{24\over 9 }::k :{14\over 13}$$