Students A, B, and C come to ask you different questions at the same time, and you explain to them the time required (7 minutes for A, 8 minutes for B, and 5 minutes for C). How would you arrange it to minimize the total waiting time of the three students?
甲、乙、丙三位同学同时来向你请教不同的问题，你给他们讲清所需的时间(甲7分钟、乙8分钟、丙5分钟)．要使三位同学所等候的时间总和最少，你将如何安排？
<gadget id="calculator">5 * 3</gadget>
<output>15</output>

<gadget id="calculator">7 * 2</gadget>
<output>14</output>

<gadget id="calculator">15 + 14 + 8</gadget>
<output>37</output>

<result>37</result>