Xiao Ming wants to find someone on the 6th floor of a building. If it takes 20 seconds to go from the 1st floor to the 3rd floor, how many seconds does it take him to go from the 3rd floor to the 6th floor at the same speed.
小明要到一座大楼的第6层找人，如果从1楼到3楼要20秒，那么他以相同的速度从3层到6层需要多少秒．
<gadget id="calculator">3 - 1</gadget>
<output>2</output>

<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<gadget id="calculator">6 - 3</gadget>
<output>3</output>

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

<result>30</result>