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: kathleen can paint a room in 4 hours, and anthony can paint an identical room in 5 hours. how many hours would it take kathleen and anthony to paint both rooms if they work together at their respective rates ?
Options: a. 8 / 15, b. 40 / 9, c. 15 / 8, d. 9 / 4, e. 15 / 4
[A]: b


[Q]: Problem: a worker is paid a regular rate of rs. 30 for completing a survey. the worker completes 100 surveys per week. for any survey involving the use of her cellphone, she is paid at a rate of that is 20 % higher than her regular rate. if she completed 50 surveys involving the use of her cellphone, how much did she get that week ?
Options: a. 2200, b. 1100, c. 2500, d. 2800, e. 3300
[A]: e


[Q]: Problem: a is twice as good a workman as b and they took 6 days together to do the work b alone can do it in.
Options: a. 18 days, b. 12 days, c. 29 days, d. 25 days, e. 27 days
[A]:
a