Xiao Ming lives on the 6th floor. If it takes Xiao Ming 20 seconds to go from the 1st floor to the 3rd floor, how many seconds will it take him to get home from the 3rd floor at the same speed?
小明家住6楼，如果从1楼到3楼小明用了20秒，那么他以同样的速度从3楼到家还需要多少秒．
<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>