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 train traveled the first d miles of its journey it an average speed of 50 miles per hour, the next d miles of its journey at an average speed of y miles per hour, and the final d miles of its journey at an average speed of 160 miles per hour. if the train ’ s average speed over the total distance was 96 miles per hour, what is the value of y ?
Options: a. 68, b. 84, c. 90, d. 120, e. 160
[A]: e


[Q]: Problem: at a florist shop on a certain day, all corsages sold for either $ 20 or $ 30. if 10 of the corsages that sold for $ 30 had instead sold for $ 20, then the store ' s revenue from corsages that day would have been reduced by 20 percent. what was the store ' s actual revenue from corsages that day ?
Options: a. $ 200, b. $ 400, c. $ 500, d. $ 800, e. $ 1000
[A]: c


[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 70 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. 15, b. 20, c. 40, d. 42, e. 68
[A]:
d