TASK DEFINITION: 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.
PROBLEM: Problem: how many quarters are equal to 7 dollars ?
Options: a. 1, b. 28, c. 12, d. 9, e. 7

SOLUTION: b

PROBLEM: Problem: if the population of a certain country increases at the rate of one person every 15 seconds, by how many persons does the population increase in 25 minutes ?
Options: a. 80, b. 100, c. 150, d. 240, e. 300

SOLUTION: b

PROBLEM: Problem: a can do a piece of work in 4 days. b can do it in 10 days. with the assistance of c they completed the work in 2 days. find in how many days can c alone do it ?
Options: a. 22 days, b. 20 / 3 days, c. 67 days, d. 17 / 6 days, e. 18 days

SOLUTION:
b