The clock knocks 3 times at 3 o'clock, and it takes 6 seconds to finish knocking, and it knocks 9 times at 9 o'clock, how many seconds to finish knocking.
时钟3时敲3下，6秒钟敲完，9时敲了9下，多少秒钟敲完．
<gadget id="calculator">3 - 1</gadget>
<output>2</output>

<gadget id="calculator">6 / 2</gadget>
<output>3</output>

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

<gadget id="calculator">3 * 8</gadget>
<output>24</output>

<result>24</result>