Someone invests $24000 \mathrm{~K}$; part of it at $4.5 \%$, the other part at $6 \%$. Their income is the same as if the entire amount earned $5 \%$ interest. How much is invested at $4.5 \%$ and how much at $6 \%$?
If $x$ korona is invested at $4.5\%$ interest, then according to the condition,

$$
\frac{4.5 x}{100}+\frac{6(24000-x)}{100}=\frac{5 \cdot 24000}{10}
$$

from which

$$
x=16000
$$

Thus, $16000$ korona is invested at $4.5\%$ and $8000$ korona at $6\%$.

(Dénes Miklós, Budapest.)

Number of solutions: 32.