If it takes 9 minutes to saw a piece of wood into 3 pieces, how many minutes will it take to saw it into 4 pieces?
把一根木头锯成三段要用9分钟，如果锯成4段要用多少分钟．
<gadget id="calculator">3 - 1</gadget>
<output>2</output>

<gadget id="calculator">9 / 2</gadget>
<output>9/2 = around 4.5</output>

<gadget id="calculator">4 - 1</gadget>
<output>3</output>

<gadget id="calculator">(9/2) * 3</gadget>
<output>27/2 = around 13.5</output>

<result>27/2 = around 13.5</result>