instruction:
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.
question:
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
answer:
D


question:
A bicyclist riding at 12 miles an hour for 2 hours travels twice the distance a hiker travels walking at 4 miles an hour for how many hours?
(A)2 (B)3 (C)4 (D)5 (E)6
answer:
B


question:
After 4 new people entered the elevator and 2 people left the elevator, there were 2 times as many people as before. How many people were in the elevator before the changes?
(A)1 (B)2 (C)4 (D)6 (E)8
answer:

B