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: by selling 15 pencils for a rupee a man loses 20 %. how many for a rupee should he sell in order to gain 20 % ?
Options: a. 8, b. 7, c. 6, d. 4, e. 10
[EX A]: e

[EX Q]: Problem: 6 men and 8 women can complete a work in 10 days. 26 men and 48 women can finish the same work in 2 days. 15 men and 20 women can do the same work in - days.
Options: a. 4 days, b. 6 days, c. 2 days, d. 8 days, e. 10 days
[EX A]: a

[EX Q]: Problem: a dishonest dealer professes to sell goods at the cost price but uses a weight of 920 grams per kg, what is his percent ?
Options: a. 22 %, b. 25 %, c. 77 %, d. 99 %, e. 8.7 %
[EX A]:
e