It takes 6 minutes to saw a piece of wood into 3 sections. According to this calculation, how many minutes will it take to saw 7 sections? (Solution with proportional knowledge)
将一分木料锯3段要6分钟，照这样计算，锯成7段要多少分钟？(用比例知识解)
<gadget id="calculator">6 * 7</gadget>
<output>42</output>

<gadget id="calculator">42 - 6</gadget>
<output>36</output>

<gadget id="calculator">3 - 1</gadget>
<output>2</output>

<gadget id="calculator">36 / 2</gadget>
<output>18</output>

<result>18</result>