Uncle Wang walked from the East Village to the West Village. After walking 40% of the journey, he was still 2.5 kilometers away from the midpoint of the journey. How many kilometers is the distance between the east and west villages?
王伯伯从东村步行去西村，走了全程的40%后离全程中点还有2.5千米，东西两村间的路程是多少千米？
<gadget id="calculator">50 / 100</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(1/2) - (2/5)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">2.5 / (1/10)</gadget>
<output>25</output>

<result>25</result>