On a map with a scale of 1:4000000, the measured distance between the two places is 6 cm. A fast car and a slow car drive from the two places simultaneously at an average speed of 60 kilometers per hour and 40 kilometers per hour. Out, how many hours can the cars meet?
在一张比例尺为1：4000000的地图上，量的两地之间的距离为6厘米，一辆快车和一辆慢车分别以平均每小时60千米、40千米的速度从两地同时开出，几小时后辆车可以相遇？
<gadget id="calculator">1 / 4_000_000</gadget>
<output>1/4_000_000 = around 0</output>

<gadget id="calculator">60 + 40</gadget>
<output>100</output>

<gadget id="calculator">6 / (1/4_000_000) / 100_000 / 100</gadget>
<output>12/5 = around 2.4</output>

<result>12/5 = around 2.4</result>