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: ramesh purchased a refrigerator for rs. 12500 after getting a discount of 20 % on the labelled price. he spent rs. 125 on transport and rs. 250 on installation. at what price should it be sold so that the profit earned would be 18 % if no discount was offered ?
Options: a. 17608, b. 17606, c. 17604, d. 17600, e. 18880
[EX A]: e

[EX Q]: Problem: arjun started a business with rs. 20,000 and is joined afterwards by anoop with rs. 30, 000. after how many months did anoop join if the profits at the end of the year are divided equally ?
Options: a. 3, b. 4, c. 5, d. 6, e. 7
[EX A]: b

[EX Q]: Problem: a certain fraction is equivalent to 2 / 5. if the numerator of the fraction is increased by 4 and the denominator is doubled, the new fraction is equivalent to 1 / 4. what is the sum of the numerator and denominator of the original fraction ?
Options: a. 49, b. 35, c. 56, d. 26, e. 21
[EX A]:
c