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: micheal and adam can do together a piece of work in 20 days. after they have worked together for 15 days micheal stops and adam completes the remaining work in 10 days. in how many days micheal complete the work separately.
Options: a. 40 days, b. 100 days, c. 120 days, d. 110 days, e. 90 days
[EX A]: a

[EX Q]: Problem: the speed of the boat in still water in 12 kmph. it can travel downstream through 48 kms in 3 hrs. in what time would it cover the same distance upstream ?
Options: a. 8 hours, b. 6 hours, c. 4 hours, d. 5 hours, e. 6 hours
[EX A]: e

[EX Q]: Problem: a is twice as good a work man as b and together they finish a piece of work in 36 days. the number of days taken by b alone to finish the work is :
Options: a. 100 days., b. 108 days., c. 98 days., d. 47 days., e. 103 days.
[EX A]:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
b

