On a map with a scale of 1:4000000, the distance between A and B is 7.5 cm. How many kilometers is the actual distance between A and B? If a train travels from A to B at a speed of 100 kilometers per hour, how long will it take to reach B?
在一张比例尺是1：4000000的地图上量得甲、乙两地的距离是7.5厘米，甲、乙两地的实际距离是多少千米？如果一辆火车以每小时100千米的时速从甲地开往乙地，几小时可以到达乙地？
<gadget id="calculator">1 / 4_000_000</gadget>
<output>1/4_000_000 = around 0</output>

<gadget id="calculator">7.5 / (1/4_000_000) / 100_000 / 100</gadget>
<output>3</output>

<result>3</result>