The newly developed printer can print 45 pages per minute, while an old-fashioned printer can only print 9 pages per minute. If you print a 135-page document, how much time can you save with a newly developed printer compared to an old one?
最新开发的打印机每分钟可以打印45页纸，而一台老式打印纸每分钟只能打印9页纸．如果打印135页的文稿，用新开发的打印机打印比老式打印机可以省多少时间？
<result>6</result>