It took 20 seconds for a signal light on a lighthouse to flash 5 times. How many flashes at most in 30 seconds.
一个灯塔上的信号灯，闪5下用了20秒．30秒最多闪多少下．
<gadget id="calculator">5 - 1</gadget>
<output>4</output>

<gadget id="calculator">20 / 4</gadget>
<output>5</output>

<gadget id="calculator">30 / 5</gadget>
<output>6</output>

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

<result>7</result>