Two trains, A and B, depart from A and B at the same speed at the same time, and meet each other after 6 hours. After the encounter, the two trains continue to run at the original speed, and after another 4 hours, A arrives at B. Ask car B to pass for a few hours before arriving at place A.
甲、乙两列火车分别从A、B两地同时相对等速度开出，经过6小时相遇，相遇后两车按原来的速度继续行驶，又经过4小时，甲车到达B地．求乙车再经过几小时，才会到达A地．
<gadget id="calculator">4 / 6</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">6 / (2/3)</gadget>
<output>9</output>

<result>9</result>