Quantitative Aptitude - Arithmetic Ability Questions

In the following question, select the odd letter/letters from the given alternatives.

Select the odd word/letters/number/number pair from the given alternatives.

If 5/2 - (6/5)(x - 15/2) = -x/5, then what is the value of x?

If a3 + 3a2 + 9a = 1, then what is the value of a3 + (3/a)?

The difference between the compound interest (compounding annually) and simple interest on a sum at the rate of 12% per annum for 2 years is Rs 360. What is the sum (in Rs)?

Simplify 437bxaz / 23ab.

What is the sum of all natural numbers between 100 and 400 which are divisible by 13?

Between 200 and 400 how many numbers are divisible by 7?