It takes 20 minutes to saw a water pipe into 5 sections, and how many minutes to saw it into 10 sections.
一根水管锯成5段要20分钟，锯成10段要多少分钟．
<gadget id="calculator">5 - 1</gadget>
<output>4</output>

<gadget id="calculator">20 / 4</gadget>
<output>5</output>

<gadget id="calculator">10 - 1</gadget>
<output>9</output>

<gadget id="calculator">5 * 9</gadget>
<output>45</output>

<result>45</result>