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 student travels from his house to school at 10 km / hr and reaches school 2 hours late. the next day he travels 18 km / hr and reaches school 1 hour early. what is the distance between his house and the school ?
Options: a. 65.0, b. 67.5, c. 70.0, d. 72.5, e. 75.0
[A]: b

[Q]: Problem: the l. c. m of two numbers is 495 and their h. c. f is 5. if the sum of the numbers is 100, then their difference is
Options: a. 19, b. 10, c. 28, d. 27, e. 29
[A]: b

[Q]: Problem: a bag of potatoes weighs 50 lbs divided by half of its weight. how much does the bag of potatoes weigh ?
Options: a. 10 lb, b. 20 lb, c. 30 lb, d. 40 lb, e. 50 lb
[A]:
a