The distance between the poles along the railway is 40 meters. A passenger is on a running train. It takes exactly 2 minutes from seeing the first pole to seeing the 51st pole. How many kilometers does the train travel per hour?
铁路沿线的电杆间隔是40米，某旅客在运行的火车中，从看到第一根电线杆到看到第51根电线杆正好是2分钟，火车每小时行多少千米．
<gadget id="calculator">51 - 1</gadget>
<output>50</output>

<gadget id="calculator">50 / 2</gadget>
<output>25</output>

<gadget id="calculator">60 / 1_000</gadget>
<output>3/50 = around 0.06</output>

<gadget id="calculator">40 * 25 * (3/50)</gadget>
<output>60</output>

<result>60</result>