VI-1 A car traveled $150 \mathrm{~km}$ in 4 hours. In the first hour, it traveled $\frac{4}{15}$ of the distance, in the second hour, it traveled $\frac{5}{8}$ of the distance it covered in the first hour, and in the third hour, it traveled $\frac{2}{3}$ of the distance it covered in the first and second hours combined. How many kilometers did it travel in the fourth hour?
Solution. The path traveled by the car in kilometers is:

- first hour: $\frac{4}{5} \cdot 150=40 \mathrm{~km}$; second hour: $\frac{5}{8} \cdot 40=25 \mathrm{~km}$;
- third hour: $\frac{2}{3} \cdot(40+25)=\frac{2}{3} \cdot 65=43 \frac{1}{3} \mathrm{~km}$;

In the fourth hour, it traveled $150-\left(40+25+43 \frac{1}{3}\right)=41 \frac{2}{3} \mathrm{~km}$.