Given a math problem with context and a question and 5 answer choices, the task is to provide the correct answer choice based on the problem. You must choose one of the given answer choices by letter: a, b, c, d, or e; anything else is invalid.

[EX Q]: Problem: the length of a rectangular floor is more than its breadth by 100 %. if rs. 600 is required to paint the floor at the rate of rs. 3 per sq m, then what would be the length of the floor ?
Options: a. 15.0 m., b. 14.4 m., c. 12.0 m., d. 16.2 m., e. 16.5 m.
[EX A]: b

[EX Q]: Problem: in 10 years, a will be twice as old as b was 10 years ago. if a is now 5 years older than b the present age of b is
Options: a. 37, b. 38, c. 39, d. 35, e. 41
[EX A]: d

[EX Q]: Problem: if a sum of money doubles itself in 10 years at simple interest, the ratepercent per annum is
Options: a. 10, b. 12.5, c. 13, d. 13.5, e. 14
[EX A]:
a