Teacher Wang, Teacher Zhang, and Teacher Li went to the school library to borrow and return books. It takes 2 minutes for Mr. Wang to borrow a book, 5 minutes for Mr. Zhang to return one book and 5 minutes for borrowing one book, and 10 minutes for Mr. Li to return two books and borrow two books. There is only one administrator in the library. How to arrange the order in which they borrow and return books so that the total waiting time of the three teachers in the library is the least? What is the minimum total waiting time in minutes?
王老师、张老师、李老师到学校图书室借还图书．王老师借书要2分钟，张老师还一本书借一本书要5分钟，李老师还两本书借两本书要10分钟．图书室只有一位管理员，如何安排他们借书还书的顺序，才能使三位老师在图书室等候时间的总和最少？最少的等候时间总和是多少分钟？
<gadget id="calculator">3 * 3</gadget>
<output>9</output>

<gadget id="calculator">5 * 2</gadget>
<output>10</output>

<gadget id="calculator">10 * 1</gadget>
<output>10</output>

<gadget id="calculator">9 + 10 + 10</gadget>
<output>29</output>

<result>29</result>