Two cities, A and B, are 630 kilometers apart. A passenger train and a freight train depart from the two cities at the same time. The passenger train travels an average of 60 kilometers per hour, and the freight train travels an average of 45 kilometers per hour. How many hours after the two trains meet?
甲乙两个城市相距630千米，一列客车和一列货车同时从两个城市相对开出，客车平均每小时行60千米，货车平均每小时行45千米，两车开出几小时后相遇？
<gadget id="calculator">60 + 45</gadget>
<output>105</output>

<gadget id="calculator">630 / 105</gadget>
<output>6</output>

<result>6</result>