B1. Brothers Janko and Peter sold a herd of 25 cows at the fair. For each cow, they received as many gold coins as there were cows in the herd. With the proceeds, they bought a herd of sheep, paying 20 gold coins for each sheep. They had just enough gold coins left to buy one lamb. They then divided the livestock so that each received an equal number of animals. The younger Peter was disadvantaged in this, as he received the lamb, which cost less than a sheep.

A How many gold coins did they receive for the herd of cows?

B How many gold coins did the lamb cost?

C How many gold coins should Janko pay Peter so that the wealth they earned from the herd of cows would be fairly divided?
B1. For each cow, they extorted 25 gold coins, for a herd of 25 cows, that's $25 \cdot 25=625$ gold coins.

B With 625 gold coins, they could buy 31 sheep, leaving them with 5 gold coins, since $625=31 \cdot 20+5$. A lamb costs 5 gold coins.

C After the division, Janko has 16 sheep, and Peter has 15 sheep and 1 lamb. Janko's herd is worth $16 \cdot 20=320$ gold coins, and Peter's is worth $15 \cdot 20+5=305$ gold coins. For a fair distribution of the wealth extorted from the cows, Janko should pay Peter $\frac{320-305}{2}=7.5$ gold coins.

## Scoring: Total: 7 points

A They received 625 gold coins for the herd. ..... $2 \mathrm{t}$
B A lamb costs 5 gold coins. ..... $2 \mathrm{t}$
C Janko should pay Peter 7.5 gold coins. ..... $3 \mathrm{t}$