instruction:
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.
question:
Problem: a 270 metres long bullet train running at the speed of 120 kmph crosses another bullet train running in opposite direction at the speed of 80 kmph in 9 seconds. what is the length of the other bullet train ?
Options: a. 226, b. 230, c. 430, d. 310, e. 260
answer:
b


question:
Problem: a store reported total sales of $ 460 million for february of this year. if the total sales for the same month last year was $ 320 million, approximately what was the percent increase in sales ?
Options: a. 2 %, b. 17 %, c. 44 %, d. 65 %, e. 83 %
answer:
c


question:
Problem: a, b and c can do a piece of work in 24 days, 30 days and 40 days respectively. they began the work together but c left 12 days before the completion of the work. in how many days was the work completed ?
Options: a. 13 days, b. 16 days, c. 18 days, d. 11 days, e. 38 days
answer:

a