If it takes 20 minutes to saw a piece of wood into 5 pieces, how many minutes will it take to saw it into 9 pieces?
一根木料锯成5段需要20分钟，若将它锯成9段需要多少分钟．
<gadget id="calculator">5 - 1</gadget>
<output>4</output>

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

<gadget id="calculator">9 - 1</gadget>
<output>8</output>

<gadget id="calculator">5 * 8</gadget>
<output>40</output>

<result>40</result>