2011 AMC 12B 第 3 题

Question

LeRoy 和 Bernardo 一起进行了一周旅行，并约定平摊费用。这一周中，他们分别支付了汽油、租车等共同费用。旅行结束时，LeRoy 共支付了

A

美元，Bernardo 共支付了

B

美元，其中

A \lt B

。LeRoy 必须给 Bernardo 多少美元，才能使两人平摊费用？

LeRoy and Bernardo went on a week-long trip together and agreed to share the costs equally. Over the week, each of them paid for various joint expenses such as gasoline and car rental. At the end of the trip it turned out that LeRoy had paid

A

dollars and Bernardo had paid

B

dollars, where

A \lt B.

How many dollars must LeRoy give to Bernardo so that they share the costs equally?

\dfrac{A+B}{2}

\dfrac{A-B}{2}

\dfrac{B-A}{2}

B-A

A+B

答案：C

知识点：代数变形

难度评级：990

小提示：

每个人最终应承担

\dfrac{A+B}{2}

美元。

Each person should end up paying

\dfrac{A+B}{2}

大提示：

LeRoy 需要补上他已付金额与公平份额之间的差额。

LeRoy must cover the gap between what he paid and his fair share

解答：

总费用为

A+B

，所以每个人的公平份额为

\dfrac{A+B}{2}

。

LeRoy 已支付

A

，少于他应承担的份额，因此他应给 Bernardo

\dfrac{A+B}{2}-A=\dfrac{B-A}{2}\text{。}

所以正确答案是 C。

The total cost is

A+B,

so each person’s fair share is

\dfrac{A+B}{2}.

LeRoy paid

A,

which is less than his share, so he must give Bernardo

\dfrac{A+B}{2}-A=\dfrac{B-A}{2}.

Thus, the correct answer is C.

2011 AMC 12B 第 3 题

答案：C

难度评级：990

小提示：

大提示：

解答：

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