Someone walks from place A to place B, and after walking the whole distance (2/5), there is still 2.5 kilometers away from the midpoint. Ask how many kilometers are the distance between A and B.
某人从甲地步行到乙地，走了全程的(2/5)之后，离中点还有2.5公里．问甲乙两地距离多少公里．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">2 / 5</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>