The fast and slow trains depart from stations A and B at the same time. When the express train arrives at the midpoint of the two stations, the local train is still 12.5 kilometers away from the midpoint. When the express train arrives at station B, the slow train travels the entire distance (7 /8), how many kilometers is the distance between stations A and B?
快慢两车分别从A、B两站同时相对开出，当快车到达两站的中点时，慢车离中点还有12.5千米，当快车到达B站时，慢车行了全程的(7/8)，A、B两站相距多少千米？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">7 / 8</gadget>
<output>7/8 = around 0.875</output>

<gadget id="calculator">(7/8) / 2</gadget>
<output>7/16 = around 0.4375</output>

<gadget id="calculator">(1/2) - (7/16)</gadget>
<output>1/16 = around 0.0625</output>

<gadget id="calculator">12.5 / (1/16)</gadget>
<output>200</output>

<result>200</result>