Mr. Krbec with his cat Kokeš were selling tickets at Kulikov Castle. On Saturday, they sold 210 children's tickets for 25 groschen each and also some adult tickets for 50 groschen each. In total, they earned 5950 groschen that day.

How many adult tickets did they sell?

(M. Krejčová)

Hint. How much did they earn from the adult tickets?
Mr. Krbec with the cat Kokeš collected a total of $210 \cdot 25=5250$ groschen for children's tickets. They collected $5950-5250=700$ for adult tickets. Therefore, they sold $700: 50=14$ of these tickets.