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.
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Question: The total monthly cost c to send \(x\) text messages is given by the function \(C(x) = 0.05x - 2.5\) for all \(x \geq 51\). If Hannah received a bill for \$10.50 for sending text messages last month, how many text messages did she send?
(A)60 (B)125 (C)160 (D)225 (E)260

Answer: E


Question: 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

Answer: D


Question: David has 4 less than one-half the number of balloons that Katie has. If David has d balloons, and Katie has k balloons, which of the following equations correctly expresses the relationship between \(d\) and \(k\) ?
(A)\(d = \frac { 1 } { 2 } (k + 4)\) (B)\(d = \frac { 1 } { 2 } (k - 4)\) (C)\(d = \frac { 1 } { 2 } k + 4\) (D)\(d = \frac { 1 } { 2 } k - 4\) (E)\(d = 2 (k - 4)\)

Answer:
D