The big clock on the square rings 5 times at 5 o'clock, it takes 8 seconds to finish the ringing, and it rings 12 times at 12 o'clock, how many seconds does it take.
广场上的大钟5时敲响5下，8秒敲完，12时敲响12下，需要多少秒．
<gadget id="calculator">5 - 1</gadget>
<output>4</output>

<gadget id="calculator">8 / 4</gadget>
<output>2</output>

<gadget id="calculator">12 - 1</gadget>
<output>11</output>

<gadget id="calculator">2 * 11</gadget>
<output>22</output>

<result>22</result>