5. A car left city A heading towards city B, covering $12 \mathrm{~km}$ in 10 minutes. At the same time, a truck left city B heading towards city A, covering 10 $\mathrm{km}$ in 12 minutes. How many kilometers apart will the car and the truck be after 2 hours and 30 minutes of driving if the distance between cities A and B is $300 \mathrm{~km}$?

NATIONAL COMPETITION IN MATHEMATICSŠibenik, April 2-4, 2014.6th grade-elementary school
5. A car travels $12 \cdot(60: 10)=72 \text{ km}$ in 1 hour (60 minutes).

A car travels $36 \text{ km}$ in 30 minutes.

A car travels $2 \cdot 72+36=144+36=180 \text{ km}$ in 2 hours and 30 minutes.

A truck travels $10 \cdot(60: 12)=50 \text{ km}$ in 1 hour.

A truck travels $25 \text{ km}$ in 30 minutes.

A truck travels $2 \cdot 50+25=125 \text{ km}$ in 2 hours and 30 minutes.

Since $180+125=305>300$, the car and the truck will meet on the road and continue further to their destination.

Their distance after 2 hours and 30 minutes will be $180+125-300=5 \text{ km}$.

## NATIONAL MATHEMATICS COMPETITION

Šibenik, April 2-4, 2014.