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:
Thirty years ago, Mr. and Mrs. Lopez purchased a house. On average, the value of the house has doubled every 6 years. If the house is worth \$320,000 today, what did they pay for it 30 years ago?
(A)\$5,000 (B)\$10,000 (C)\$64,000 (D)\$160,000 (E)\(\$320,000 \times 2^5\)
answer:
B


question:
Stephanie, Damon, and Karissa have been contracted to paint an office building that contains 72 rooms. If Stephanie paints half as many rooms as Karissa and 12 more than Damon, how many rooms does Karissa paint?
(A)9 (B)21 (C)30 (D)42 (E)48
answer:
D


question:
On a certain test, if a student answers 80 to 90 percent of the questions correctly, he will receive a letter grade of B. If there are 40 questions on the test, what is the minimum number of questions the student can answer correctly to receive a grade of B?
(A)24 (B)28 (C)32 (D)33 (E)36
answer:

C