It takes 5 minutes to saw a piece of wood of uniform thickness into 2 pieces, how many minutes will it take to saw it into 4 pieces now?
把一根粗细均匀的木头锯成2段需要的时间是5分，现要锯成4段需多少分．
<gadget id="calculator">2 - 1</gadget>
<output>1</output>

<gadget id="calculator">5 / 1</gadget>
<output>5</output>

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

<gadget id="calculator">5 * 3</gadget>
<output>15</output>

<result>15</result>