To build a section of road, it was originally planned to be completed by 120 people in 50 days. After working for one month (calculated as 30 days), 20 people were transferred away to rush to repair other road sections. In this way, how many more days will the remaining people need to work than the original plan to complete the task?
修一段公路，原计划120人50天完工．工作一月(按30天计算)后，有20人被调走，赶修其他路段．这样剩下的人需比原计划多干多少天才能完成任务？
<gadget id="calculator">1 / 50</gadget>
<output>1/50 = around 0.02</output>

<gadget id="calculator">1 / 120</gadget>
<output>1/120 = around 0.008333</output>

<gadget id="calculator">(1/50) * (1/120) * 20 * 20</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">(1/50) * (1/120) * 100</gadget>
<output>1/60 = around 0.016667</output>

<gadget id="calculator">(1/15) / (1/60)</gadget>
<output>4</output>

<result>4</result>