There are many visitors lining up before the amusement park opens. The number of visitors that join the line each minute is constant, which is 10 visitors per minute. Each entrance can help 25 visitors check in per minute. If there is one entrance, there will be no one waiting in the line after 16 min. If there are 2 entrances, how long after will there be no one waiting in the line? 
Overseas Competition->Knowledge Point->Word Problem Modules->Newton's Problem of Cows and Fields