If it takes Xiaojun 1 minute and 20 seconds to go up from the first floor to the fifth floor, how many seconds does it take Xiaojun to go up each floor?
若小军从一楼上到五楼，共用了1分20秒，则小军每上一层要用多少秒．
<gadget id="calculator">5 - 1</gadget>
<output>4</output>

<gadget id="calculator">80 / 4</gadget>
<output>20</output>

<result>20</result>