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: if john makes a contribution to a charity fund at school, the average contribution size will increase by 50 % reaching $ 75 per person. if there were 1 other contributions made before john ' s, what is the size of his donation ?
Options: a. $ 100, b. $ 150, c. $ 200, d. $ 250, e. $ 450
[EX A]: a

[EX Q]: Problem: a man spends 2 / 5 of his salary on house rent, 3 / 10 of his salary on food and 1 / 8 of his salary on convenience he has rs. 1400 left with him, find his expenditure on food and conveyance.
Options: a. 1000, b. 3000, c. 4000, d. 2000, e. 5000
[EX A]: a

[EX Q]: Problem: a, b and c are partners in a business. their capitals are respectively, rs. 5000, rs. 6000 and rs. 4000. a gets 30 % of the total profit for managing the business. the remaining profit is divided among 3 in the ratio of their capitals. in the end of the year, the profit of a is rs. 200 more than the sum of the profits of b and c. find the total profit ?
Options: a. 3089, b. 3098, c. 3057, d. 3000, e. 3012
[EX A]:
d