The length of the railway between two cities A and B is 745 kilometers. A passenger car travels from city A to city B at a speed of 85 kilometers per hour. One hour later, a freight train leaves city B at a speed of 80 kilometers per hour. To Jiacheng. How many hours later will the two cars meet?
甲、乙两城市之间的铁路长745千米，一列客车以每小时85千米的速度从甲城开往乙城，1小时后有一列货车以每小时80千米的速度从乙城开往甲城．再经过多少小时两车相遇？
<gadget id="calculator">745 - 85</gadget>
<output>660</output>

<gadget id="calculator">85 + 80</gadget>
<output>165</output>

<gadget id="calculator">660 / 165</gadget>
<output>4</output>

<result>4</result>