Honzík received his pocket money and wants to buy something nice with it. If he bought four rolls, he would have 5 Kč left. If he wanted to buy five rolls, he would be short of 6 Kč. If he bought two rolls and three pretzels, he would spend his entire pocket money without any remainder.

How much does one pretzel cost?

(L. Dedková)

Hint. How much does one roll cost?
Honzík's pocket money can be expressed in three ways, namely as

- the sum of the price of 4 cakes plus 5 Kč,
- the sum of the price of 5 cakes minus 6 Kč,
- the sum of the prices of 2 cakes and 3 pretzels.

From the first two expressions, it follows that one cake costs $5+6=11$ Kč. From this, we also find that Honzík's pocket money was $4 \cdot 11+5=5 \cdot 11-6=49$ Kč. From the third expression, it follows that for three pretzels, Honzík would pay $49-2 \cdot 11=27$ Kč. Therefore, one pretzel costs $27: 3=9$ Kč.