Xiao Ming sat at the window of the train, and the train drove from the south end of the bridge to the north end. Xiao Ming measured the elapsed time as 35 seconds. Dad asked Xiao Ming how long the bridge was, so Xiao Ming immediately timed 25 seconds from a certain telegraph pole next to the railway to the 10th telegraph pole. If the distance between every two electric poles on the roadside is 50 meters, Xiao Ming can calculate the length of the bridge in meters.
小明坐在火车的窗口位置，火车从大桥的南端驶向北端，小明测得共用时35秒．爸爸问小明这座桥有多长，于是小明马上从铁路旁的某一根电线杆计时到第10根电线杆用时25秒．如果路旁每两根电线杆的间隔为50米，小明就可算出了大桥的长度为多少米．
<gadget id="calculator">10 - 1</gadget>
<output>9</output>

<gadget id="calculator">9 / 25</gadget>
<output>9/25 = around 0.36</output>

<gadget id="calculator">50 * (9/25) * 35</gadget>
<output>630</output>

<result>630</result>