The highway between cities A and B is 600 kilometers long. A car travels from city A to city B at 80 kilometers per hour, and an off-road vehicle travels from city B to city A at 70 kilometers per hour. rice. Two cars depart at the same time, how many hours will they meet?
A、B两城间的高速公路长600千米，一辆小轿车从A城开往B城，每小时行80千米，一辆越野车从B城开往A城，每小时行70千米．两车同时出发，几小时后能相遇？
<gadget id="calculator">80 + 70</gadget>
<output>150</output>

<gadget id="calculator">600 / 150</gadget>
<output>4</output>

<result>4</result>