It took Xiaodong 30 seconds to walk from the first floor to the fourth floor, so how many seconds does it take him to walk to the eighth floor?
小东从一楼走到4楼用了30秒，那么他要走到8楼共需要多少秒．
<gadget id="calculator">4 - 1</gadget>
<output>3</output>

<gadget id="calculator">30 / 3</gadget>
<output>10</output>

<gadget id="calculator">8 - 1</gadget>
<output>7</output>

<gadget id="calculator">10 * 7</gadget>
<output>70</output>

<result>70</result>