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: if 80 percent of a class answered the first question on a certain test correctly, 55 percent answered the second question on the test correctly, and 20 percent answered neither of the questions correctly, what percent answered both correctly ?
Options: a. 10 %, b. ( 8 ) 20 %, c. 30 %, d. 50 %, e. 55 %
[A]: e


[Q]: Problem: if the range q of the 6 numbers 4, 314, 710 and x is 12, what is the difference between the greatest possible value of x and least possible value of x ?
Options: a. 0, b. 2, c. 12, d. 13, e. 15
[A]: d


[Q]: Problem: a man swims downstream 72 km and upstream 45 km taking 6 hours each time; what is the speed of the current ?
Options: a. 2.28, b. 2.24, c. 2.27, d. 2.25, e. 2.23
[A]:
d