The Zhengzhou-Shijiazhuang railway is 420 kilometers long. A train departs from Zhengzhou at 10:30 am and arrives at Shijiazhuang at 2:30 pm. Find the average speed of this train?
郑州到石家庄铁路长420千米，一列火车上午10时30分从郑州出发，下午2时30分到达石家庄，求这列火车平均速度？
<gadget id="calculator">420 / 4</gadget>
<output>105</output>

<result>105</result>