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.

[EX Q]: Problem: car x began traveling at an average speed of 35 miles per hour. after 72 minutes, car y began traveling at an average speed of 49 miles per hour. when both cars had traveled the same distance, both cars stopped. how many miles did car x travel from the time car y began traveling until both cars stopped ?
Options: a. 105, b. 120, c. 140, d. 147, e. 168
[EX A]: a

[EX Q]: Problem: 1 men takes 37 $ to eat a pizza in restaurant such that it have discount multiple of 4 if u eat more pizza. discount increase by multiple of 4 every pizza u eat. for 1 pizza 0 % off. for 2 pizza % off for 3 pizza 8 % off. pizza without discount is 10 $. how much that man eats the pizza.
Options: a. 2, b. 3, c. 4, d. 5, e. 6
[EX A]: b

[EX Q]: Problem: a trained covered x km at 90 kmph and another 2 x km at 20 kmph. find the average speed of the train in covering the entire 3 x km.
Options: a. 22, b. 99, c. 27, d. 66, e. 887
[EX A]:
c