If it takes 15 minutes to saw a piece of wood into 5 sections, how many minutes will it take to saw the same piece of wood into 7 sections at the same speed?
如果把一根木料锯成5段用15分钟，那么用同样的速度把这根木料锯成7段，要用多少分钟？
<gadget id="calculator">5 - 1</gadget>
<output>4</output>

<gadget id="calculator">15 / 4</gadget>
<output>15/4 = around 3.75</output>

<gadget id="calculator">7 - 1</gadget>
<output>6</output>

<gadget id="calculator">(15/4) * 6</gadget>
<output>45/2 = around 22.5</output>

<result>45/2 = around 22.5</result>