其它
The distance between A and B is $$350$$ $\text{km}$. Kin and Mary drive away from A and B respectively at $8$ a.m. and go towards each other at same time. Kin drives $$40$$ $\text{km/h}$, and Mary drives $$50$$ $\text{km/h}$. 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  $$8+2+3=13$$ 