steel pipe is 12 meters long. It takes 20 minutes to saw it into sections of 4 meters each. How many minutes does it take to saw one time?
一根钢管长12米，要把它锯成每4米的一段，共需要20分钟，锯一次需要多少分钟？
<gadget id="calculator">12 / 4</gadget>
<output>3</output>

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

<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<result>10</result>