## 291. Math Puzzle $8 / 89$

An expedition covers 2/5 of the distance on the 1st day, 1/3 on the 2nd day, and the remaining $100 \mathrm{~km}$ on the 3rd day.

What total distance was covered by the expedition participants?
$\frac{2}{5} x+\frac{1}{3} x+100=x ; \quad x=375$

This leads to: The expedition covers $150 \mathrm{~km}$ on the first day, $125 \mathrm{~km}$ on the second day, and $100 \mathrm{~km}$ on the third day, totaling $375 \mathrm{~km}$.