A train travels from place A to place B. It travels the whole distance (3/8) in the first hour, and travels the whole distance (3/10) in the second hour. It travels 140 kilometers more than half the distance in two hours. ． How long is the railway from A to B?
一列火车从甲地到乙地，第一个小时行了全程的(3/8)，第二个小时行了全程的(3/10)，两个小时行的比全程的一半多140千米．甲地到乙地的铁路长多少千米？
<gadget id="calculator">3 / 8</gadget>
<output>3/8 = around 0.375</output>

<gadget id="calculator">3 / 10</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(3/10) - (1/2)</gadget>
<output>-1/5 = around -0.2</output>

<gadget id="calculator">(3/8) + (-1/5)</gadget>
<output>7/40 = around 0.175</output>

<gadget id="calculator">140 / (7/40)</gadget>
<output>800</output>

<result>800</result>