train travels from point A to point B. It has traveled the entire distance (3/5), and it is still 100 kilometers away from point B. How long is the railway between AB and AB?
一列火车从A地开往B地，已经行了全程的(3/5)，离B地还有100千米．AB两地之间的铁路长多少千米？
<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">1 - (3/5)</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">100 / (2/5)</gadget>
<output>250</output>

<result>250</result>