数学题：早上7点，甲乙两人从A、B两地同时出发相向而行，甲每小时比乙每小时多行x千米，x为整数，在距离AB的中点10千米处，甲与乙第一次相遇，之后乙继续前行于下午到达A地等待甲回来，甲到达B地后立即返还，于下午5:00到达A地，问乙等了甲多长时间？

数学题解答：

推荐阅读：
Unobvious Life Hacks for Ads Optimization in Google　 Essential Traits That Will Help Bloggers Work From Home Successf　 Examining the Physical and Mental Health of Writers and Bloggers　 How will Blogging Change after the Pandemic?　 Digital Relationships: 5 Tips For Building A Better Veterinary B　 The 2020 Pandemic Further Boosts Earnings and Influence of Blogg　 What to Do When Your Blog Gets Too Big for You Alone　 Minimum Numbers of Function Calls to Make Target Array　 Harddrives will fail – it is just a matter of when　 Bruteforce/DFS/Backtracking Algorithm using Javascript to Solve