Teacher Li downloaded a file on the computer, and the download time has passed 15 minutes, and the completion is 75%, so how many minutes will Teacher Li wait to download the file.
李老师在电脑上下载一份文件，下载时间已过去了15分钟，完成了75%，那么李老师还要等多少分钟才能下载完这份文件．
<gadget id="calculator">75 / 100</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">15 / (3/4)</gadget>
<output>20</output>

<gadget id="calculator">20 - 15</gadget>
<output>5</output>

<result>5</result>