Uncle Wang set off at 10:00 last night and drove a total of 450 kilometers to reach the destination at 7:00 the next day. How many kilometers per hour does he drive on average?
王叔叔昨天晚上10：00出发，第二天7：00到达目的地一共行驶了450千米，他平均每小时行驶多少千米？
<gadget id="calculator">450 / 9</gadget>
<output>50</output>

<result>50</result>