In the morning, Teacher Zhang rode a motorcycle from school to the library. At 10:15 in the morning, Teacher Wang also drove from school to the library along the same route. At 10:25, the distance between the two was 2.5 kilometers. 35 The distance between the two is still 2.5 kilometers. Teacher Wang arrived at the library at 10:45, and Teacher Zhang arrived at the library at 11:00. At what point did Teacher Zhang leave?
早晨，张老师骑摩托车从学校出发去图书馆，上午10：15，王老师开车也从学校出发沿同样的路线前往图书馆，10：25两人之间的距离是2.5千米，10：35两人之间的距离还是2.5千米，10：45王老师到达图书馆，11：00张老师到达图书馆，则张老师是在多少点出发的．
<result>10</result>