A car goes back and forth between A and B. It takes 5 hours to go, and the speed increases (1/6) when it returns. How many hours does it take to return?
一辆汽车往返于甲、乙两地，去时用了5小时，回来时速度提高了(1/6)，回来时用了多少小时？
<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<result>2/7 = around 0.285714</result>