From place A to place B, the whole distance traveled on the first day (2/5), compared with the distance traveled on the second day is 4:5, at this time there is still 80 kilometers away from place B, find the distance between places A and B ．
从甲地到乙地，第一天行了全程的(2/5)，与第二天所行路程比是4：5，这时离乙地还有80千米，求甲乙两地间路程．
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">5 / 4</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">(2/5) * (5/4)</gadget>
<output>1/2 = around 0.5</output>

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

<gadget id="calculator">80 / (1/10)</gadget>
<output>800</output>

<result>800</result>