On a traffic map with a scale of 1:15,000,000, the length of the railway from Beijing to Nanjing is measured to be 6cm. A train departs from Beijing to Nanjing and travels 120km per hour. How long does it take for the train to reach Nanjing?
在比例尺为1：15000000的交通地图上量得北京到南京的铁路长为6cm，一列火车从北京出发开往南京，每小时行120km，这列火车到达南京需多少小时？
<gadget id="calculator">1 / 15_000_000</gadget>
<output>1/15_000_000 = around 0</output>

<gadget id="calculator">6 / (1/15_000_000) / 100_000 / 120</gadget>
<output>15/2 = around 7.5</output>

<result>15/2 = around 7.5</result>