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: a sum of money at simple interest amounts to $ 645 in 3 years and to $ 690 in 4 years. the sum is :
Options: a. $ 153, b. $ 510, c. $ 598, d. $ 549, e. $ 675
[A]: b

[Q]: Problem: a fort had provision of food for 150 men for 45 days. after 15 days, 10 men left the fort. the number of days for which the remaining food will last, is :
Options: a. 32, b. 37 1 / 4, c. 42, d. 54, e. 45
[A]: a

[Q]: Problem: during a car trip, maria stopped to rest after she traveled 1 / 2 of the total distance to her destination. she stopped again after she traveled 1 / 4 of the distance remaining between her first stop and her destination, and then she drove the remaining 135 miles to her detination. what was the total distance, in miles from maria ' s starting point to her destination ?
Options: a. 280, b. 320, c. 360, d. 420, e. 480
[A]:
c