If it takes 3 seconds for a big clock to strike three times, how many seconds will it take for this big clock to strike seven times?
一只大钟敲三下要用3秒，这只大钟敲七下要用多少秒．
<gadget id="calculator">3 - 1</gadget>
<output>2</output>

<gadget id="calculator">3 / 2</gadget>
<output>3/2 = around 1.5</output>

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

<gadget id="calculator">(3/2) * 6</gadget>
<output>9</output>

<result>9</result>