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.

[Q]: Problem: a mixture of 70 litres of milk and water contains 10 % water. how many litres of water should be added to the mixture so that the mixture contains 12 1 / 2 % water ?
Options: a. 2, b. 8, c. 6, d. 3, e. 4
[A]: a


[Q]: Problem: a and b started a business in partnership investing rs. 20,000 and rs. 15,000 respectively. after 6 months, c joined them with rs. 20,000. whatwill be b ' s share in total profit of rs. 15,000 earned at the end of 2 years from the startingof the business ?
Options: a. s. 5,000, b. s. 4,500, c. s. 5,700, d. s. 6,500, e. s. 7,500
[A]: b


[Q]: Problem: a dishonest dealer claims to sell a product at its cost price. he uses a counterfeit weight which is 20 % less than the real weight. further greed overtook him and he added 40 % impurities to the product. find the net profit percentage of the dealer ?
Options: a. 94 %, b. 87.5 %, c. 55 %, d. 56.25 %, e. 36 %
[A]:
b