其它
The distance between A and B is $$350$$km. Kin and Mary drive away from A and B respectively at $8$ a.m. and go towards each other at same time. Kin drives $$40$$km/h, and Mary drives $$50$$km/h. Mary rested for $$2$$ hours on her way and then continues driving. They will meet at~\uline{~~~~~~~~~~}~. 
Overseas Competition->Knowledge Point->Calculation Modules->Fractions
$$(350-80)$$$\div$$$(40+50)=3$$hr  $$8+2+3=13$$ 