Koizumi and Xiaomei set off from cities A and B at the same time respectively, and they meet each other within 5 hours. If Xiaomei, Koizumi, and Ouou set off from City A to City B at the same time, Koizumi returns immediately after arriving in City B, meets Xiaomei after 1 hour, and meets Ouou after another 2 hours. If Koizumi and Ou Ou set off from cities A and B at the same time and walk toward each other, how many hours will it take for them to meet each other?
小泉、小美两人分别从A、B两城同时出发，相向而行，5小时相遇．若小美、小泉、欧欧三人从A城同时出发往B城走，小泉到B城后马上返回，1小时后与小美相遇，又过2小时与欧欧相遇．若小泉、欧欧两人分别从A、B两城同时出发，相向而行，则两人的相遇时间是多少小时．
<gadget id="calculator">5 * 2</gadget>
<output>10</output>

<gadget id="calculator">10 - 1</gadget>
<output>9</output>

<gadget id="calculator">9 + 1 + 2</gadget>
<output>12</output>

<gadget id="calculator">12 / 2</gadget>
<output>6</output>

<result>6</result>