On a map with a scale of 1:7500000, the distance from Nanjing to Beijing is measured to be 12 centimeters. How long does it take for a train to travel from Nanjing to Beijing at a speed of 180 kilometers per hour?
在比例尺是1：7500000的地图上，量得南京到北京的距离是12厘米，一列火车以每小时180千米的速度从南京去北京要多少小时？
<gadget id="calculator">1 / 7_500_000</gadget>
<output>1/7_500_000 = around 0</output>

<gadget id="calculator">1_000 * 100</gadget>
<output>100_000</output>

<gadget id="calculator">12 / (1/7_500_000) / 100_000 / 180</gadget>
<output>5</output>

<result>5</result>