$A$ and $B$ together have $5000 \mathrm{~K}$. $A$ placed his money at $x \%$, and $B$ placed his at $x+1 \%$. After one year, $A$ received a total of $2100 \mathrm{~K}$ in capital and interest, and $B$ received a total of $3180 \mathrm{~K}$ in capital and interest. How much money did each originally have?
Originally, $A$ had $y$ koronas, then according to the problem

$$
y+\frac{y x}{100}=2100
$$

and

$$
5000-y+\frac{5000-y}{100}(x+1)=3180
$$

Solving for $x$ from the first equation and substituting it into the second equation, we get

$$
y^{2}+523000 y-1050000000=0
$$

from which the positive value of $y$ is: $y=2000$, so originally $A$ had $2000 \mathrm{~K}$, and $B$ had $3000 \mathrm{~K}$.

(Jenö Silbermann, Nagyvárad.)