After Li Min traveled 37.5% of the journey from Dongcheng to Xicheng, he was still 3.5km away from the midpoint of the journey. How many kilometers is the distance between the east and west cities?
李敏从东城到西城，走了全程的37.5%后，距离全程中点还有3.5km，东西两城的距离是多少千米？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">37.5 / 100</gadget>
<output>0.375</output>

<gadget id="calculator">(1/2) - 0.375</gadget>
<output>0.125</output>

<gadget id="calculator">3.5 / 0.125</gadget>
<output>28</output>

<result>28</result>