GMAT
题目
From a committee of 25 legislators, n members formed a task force. Each member of the task force sent a report to each committee member who was not on the task force. If a letter was sent in response to each report, which of the following represents the combined number of reports and letters sent?
解析
总人数25，工作组 $n$ 人，非工作组为 $(25-n)$ 人。
每人发1份报告，报告总数 = $n \times (25-n)$。
每1份报告对应1封回信，回信数量也 = $n \times (25-n)$。
报告+回信 = $n(25-n) + n(25-n) = \mathbf{2n(25-n)}$。
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