Teacher Li, Teacher Wang, and Teacher Xu go to the financial office to pay the book fees at the same time. Teacher Li takes 7 minutes, Teacher Wang takes 6 minutes, and Teacher Xu takes 4 minutes. How to arrange their payment order so that these three people can pay The sum of fees and waiting time is the least? How many minutes at least?
李老师、王老师和徐老师三人同时去财务室交书费，李老师需要7分钟，王老师需要6分钟，徐老师需要4分钟，怎样安排他们的交费顺序，才能使这三个人交费和等候所用的时间总和最少？最少需要几分钟？
<gadget id="calculator">4 + 5</gadget>
<output>9</output>

<gadget id="calculator">4 + 5 + 7</gadget>
<output>16</output>

<gadget id="calculator">4 + 9 + 16</gadget>
<output>29</output>

<result>29</result>