Friendship Factory has to process 192 sets of clothing, each person processes two sets per day, and the original plan can be completed on time by 8 people. If the work efficiency of each person remains the same, and the task needs to be completed 4 days ahead of schedule, how many people need to be added for processing?
友谊厂要加工192套服装，每人每天加工两套，原计划8人可以按时完成．如果每人的工作效率不变，要提前4天完成任务，需要增加多少人加工？
<gadget id="calculator">8 * 2</gadget>
<output>16</output>

<gadget id="calculator">192 / 16</gadget>
<output>12</output>

<gadget id="calculator">12 - 4</gadget>
<output>8</output>

<gadget id="calculator">12 - 8</gadget>
<output>4</output>

<result>4</result>