middle school library purchased 3 hardcover copies and 5 paperback copies of "Chinese Dictionary" for a total of 27.8 yuan. If one hardcover is exchanged for two paperbacks, an additional 1 yuan will be charged. How much is the hardcover price per copy?
某中学图书馆购买了3本精装本、5本平装本《汉语辞典》，共用27.8元，如果用一本精装本调换两本平装本要多付1元．问精装本每本定价多少元？
<gadget id="calculator">1 * 3</gadget>
<output>3</output>

<gadget id="calculator">27.8 + 3</gadget>
<output>30.8</output>

<gadget id="calculator">2 * 3</gadget>
<output>6</output>

<gadget id="calculator">5 + 6</gadget>
<output>11</output>

<gadget id="calculator">30.8 / 11</gadget>
<output>2.8</output>

<gadget id="calculator">2.8 * 2</gadget>
<output>5.6</output>

<gadget id="calculator">5.6 - 1</gadget>
<output>4.6</output>

<result>4.6</result>