Xiaoming’s pendulum clock will automatically tell the time. It is known that the pendulum clock strikes 6 times at 6 o’clock, and it takes 15 seconds. How many seconds did it take for the clock to strike 10 times at 10 o’clock.
小明家的摆钟会自动报时，已知该摆钟6时敲响6下，共用了15秒，10点整时该钟敲了10下，用了多少秒．
<gadget id="calculator">10 - 1</gadget>
<output>9</output>

<gadget id="calculator">6 - 1</gadget>
<output>5</output>

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

<gadget id="calculator">9 * 3</gadget>
<output>27</output>

<result>27</result>