The distance between A and B is 400 kilometers. A truck drives from A to B. After driving for 4.5 hours, it is still 17.5 kilometers away from B. How many kilometers does this truck drive on average per hour?
甲、乙两地相距400千米，一辆货车从甲地开往乙地，行驶了4.5小时后离乙地还有17.5千米，这辆货车平均每小时行驶多少千米？
<gadget id="calculator">400 - 17.5</gadget>
<output>382.5</output>

<gadget id="calculator">382.5 / 4.5</gadget>
<output>85</output>

<result>85</result>