The distance between A and B is 600 kilometers. At 8:00 a.m., the bus travels from A to B at an average speed of 60 kilometers per hour. A truck travels from point B to point A at an average speed of 50 km/h. In order for the two cars to meet at the midpoint of the journey, at what time in the morning must the truck start.
甲、乙两地间的路程是600千米，上午8点客车以平均每小时60千米的速度从甲地开往乙地．货车以平均每小时50千米的速度从乙地开往甲地．要使两车在全程的中点相遇，货车必须在上午多少点出发．
<gadget id="calculator">8 - 1</gadget>
<output>7</output>

<result>7</result>