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 can do a job in 15 days and b in 20 days. if they work on it together for 4 days, then the fraction of the work that is left is ?
Options: a. 2 / 15, b. 8 / 15, c. 3 / 11, d. 1 / 12, e. 6 / 13
answer:
b


question:
Problem: find the sum of first 89 odd numbers
Options: a. 7921, b. 4800, c. 7900, d. 4980, e. 4960
answer:
a


question:
Problem: how many seconds will a train 150 meters long take to cross a bridge 150 meters long if the speed of the train is 36 kmph ?
Options: a. 28 sec, b. 23 sec, c. 29 sec, d. 30 sec, e. 36 sec
answer:

d