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: 40 is subtracted from 60 % of a number, the result is 50. find the number ?
Options: a. 150, b. 330, c. 277, d. 279, e. 712
[EX A]: a

[EX Q]: Problem: 11 is subtracted from 40 % of a number and results is 23. what is the number ?
Options: a. 160, b. 92, c. 88, d. 85, e. 34
[EX A]: d

[EX Q]: Problem: a certain list consists of 21 different numbers. if n is in the list and n is 5 times the average ( arithmetic mean ) of the other 20 numbers in the list, then n is what fraction of the sum of the 21 numbers in the list ?
Options: a. 1 / 20, b. 1 / 6, c. 1 / 5, d. 4 / 21, e. 5 / 21
[EX A]:
c