truck had to travel 500 kilometers to deliver relief supplies to the disaster area, and it was exactly half of the way by 2 pm. At this time, I was notified that I must arrive at the disaster area before 4:30 pm. At least how many kilometers per hour is the remaining distance traveled?
一辆卡车要行驶500千米往灾区运送救灾物资，到下午2时正好行了一半路程．这时接到通知，必须在下午4时30分之前到达灾区．剩下的路程至少每小时行驶多少千米？
<gadget id="calculator">500 / 2 / 2.5</gadget>
<output>100</output>

<result>100</result>