It takes 20 minutes to saw a piece of wood into 5 sections on average, how many minutes does it take on average to saw once.
一根木头平均锯成5段，共需要20分钟，平均锯一次需要多少分钟．
<gadget id="calculator">5 - 1</gadget>
<output>4</output>

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

<result>5</result>