passenger train and a freight train depart from A and B oppositely at the same time. When the two trains meet, the passenger train has traveled 70% of the journey, and the freight train is still 500 kilometers away from the midpoint of the two places. It is known that the bus takes 20 hours to complete the journey, how many kilometers does the bus travel per hour?
一列客车和一列货车同时从甲乙两地相对开出，当两列火车相遇时，客车走了全程的70%，货车距离两地的中点还有500千米．已知客车走完全程用20小时，客车每小时行多少千米？
<gadget id="calculator">70 / 100</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">1 - (7/10)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">(7/10) - (3/10)</gadget>
<output>2/5 = around 0.4</output>

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

<gadget id="calculator">500 * 5</gadget>
<output>2_500</output>

<gadget id="calculator">2_500 / 20</gadget>
<output>125</output>

<result>125</result>