You are given a mathematical question described with an open-ended vocabulary. Questions in this task involve real-world situations, describing a mathematical problem. You are also given 4 or 5 answer options (associated with "A", "B", "C", "D", "E"). Do not generate anything else apart from one of the following characters: 'A', 'B, 'C', 'D', 'E'. LaTeX mathematical format (the standard way to express mathematical expressions in the typesetting software known as LaTeX) is used to express equations. Each question is solvable with high school math knowledge. Give only one answer for each question.

[EX Q]: At a certain restaurant, there are 25 tables and each table has either 2 or 4 chairs. If there is a total of 86 chairs accompanying the 25 tables, how many tables have exactly 4 chairs?
(A)9 (B)12 (C)15 (D)18 (E)21
[EX A]: D

[EX Q]: A long-distance runner takes between 5 and 7 minutes to run one mile during the first half of a cross-country race. During the second half, she starts to get tired and adds 1 to 2 minutes to the time it takes her to run a mile. What are the minimum and maximum munber of minutes it would take the runner to run one mile during the second half of the race?
(A)5 and 7 minutes (B)6 and 8 minutes (C)6 and 9 minutes (D)7 and 8 minutes (E)7 and 9 minutes
[EX A]: C

[EX Q]: How many minutes did John take, driving at 20 miles per hour, to go the same distance that Mary took 30 minutes to drive at 60 miles per hour?
(A)10 (B)30 (C)60 (D)90 (E)180
[EX A]:
D