If $A$ contributed $x$ K to the business, then $B$ contributed $(3400-x)$ K. The profits of the business partners are $2070-x$ and $1920-(3400-x)=x-1480$, respectively. Since the profit is proportional to the time and shares, therefore:

$$
(2070-x):(x-1480)=12 x: 16(3400-x)
$$

from which $x=1800$. So $A$ contributed $1800 \mathrm{~K}$, and $B$ contributed $1600 \mathrm{~K}$ to the business.

(Neidenbach Emil, Arad.)

The problem was also solved by: Déri Zs., Ehrenstein P., Freund E., Haar A., Jánosy Gy., Kelemen M., Kürti I., Ligeti P., Pénzes Z., Raab R., Schwarz Gy., Schwimmer J., Söpkéz Gy.
$A$ and $B$ together invested $3400 \mathrm{~K}-\mathrm{t}$ in a business, with $A$ for 12 months and $B$ for 16 months. After the business ended, $A$ received $2070 \mathrm{~K}-\mathrm{t}$ in capital and profit, and $B$ received $1920 \mathrm{~K}-\mathrm{t}$. How many koronas did each contribute to the business?