Say the 77-meter-long iron wire is cut into 13 sections, some of which are 9 meters long, and some of which are 4 meters long. How many sections are there in total for the 9-meter-long section?
讲77米长铁丝截成13段，一部分每段长9米，一部分每段长4米，其中9米长一段的一共有多少段．
<gadget id="calculator">4 * 13</gadget>
<output>52</output>

<gadget id="calculator">77 - 52</gadget>
<output>25</output>

<gadget id="calculator">9 - 4</gadget>
<output>5</output>

<gadget id="calculator">25 / 5</gadget>
<output>5</output>

<result>5</result>