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: for each color copy, print shop x charges $ 1.20 and print shop y charges $ 1.70. how much greater is the charge for 40 color copies at print shop y than at print shop x ?
Options: a. $ 14, b. $ 16, c. $ 18, d. $ 20, e. $ 22
[EX A]: d

[EX Q]: Problem: if x ^ 2 – 3 x = 18, then one possible value of x – 4 =
Options: a. - 9, b. - 5, c. - 3, d. - 1, e. 2
[EX A]: e

[EX Q]: Problem: if 30 men take 15 days to to complete a job, in how many days can 25 men finish that work ?
Options: a. 18, b. 17, c. 16, d. 15, e. 14
[EX A]:
a