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: john and david can finish a job together in 2 hours. if john can do the job by himself in 3 hours, what percent of the job does david do ?
Options: a. 36.33 %, b. 33.33 %, c. 39.33 %, d. 40.33 %, e. 33 %
answer:
b

question:
Problem: for any positive integer n, the sum of the first n positive integers equals n ( n + 1 ) / 2. what is the sum of all the integers between 100 and 200 ?
Options: a. 4545, b. 5050, c. 6525, d. 4352, e. 4652
answer:
b

question:
Problem: a man can do a job in 5 days. his father takes 20 days and his son finishes it in 25 days. how long will they take to complete the job if they all work together ?
Options: a. 6.3, b. 6.9, c. 3.5, d. 6.1, e. 6.2
answer:
c