Ou Ou and Xiao Mei set off from A and B at the same time respectively, and head toward each other. When starting out, Xiaomei's speed is Oou's (4/5), after meeting, Ou's speed decreases (1/5), and Xiaomei's speed increases (1/5), so that when Ou arrives at B, Xiaomei is still 10 kilometers away from A. So, how many kilometers are there between A and B?
欧欧、小美两人分别从A、B两地同时出发，相向而行．出发时，小美的速度是欧欧的(4/5)，相遇后，欧欧的速度减少(1/5)，小美的速度增加(1/5)，这样，当欧欧到达B地时，小美距A地还有10千米．那么，A、B两地相距多少千米？
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 + (1/5)</gadget>
<output>6/5 = around 1.2</output>

<gadget id="calculator">4 * (6/5)</gadget>
<output>24/5 = around 4.8</output>

<gadget id="calculator">5 - (24/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">10 / (1/5)</gadget>
<output>50</output>

<gadget id="calculator">50 * 9</gadget>
<output>450</output>

<result>450</result>