You can only unlock the chapter using a special code that we will send you via the Viber app. Receiving a message is free of charge and with no obligations.
My phone number:
Get a code
In compliance with the law, persons under the age of 15 can enter their phone number only in the presence of a parent or guardian.
4-character (Viber) code:
Check the received code
The page will be refreshed automatically in a few seconds.
How many songs do they have to play at a party if there are 9 boys and 11 girls on the stage and each of the boys wants to dance with all the girls (each girl determines a song she will dance)?
The detailed solution steps are locked. Click on the blue button to unlock them.
To ensure the proper functioning of the website, OpenProf uses cookies that do not store personal data. By continuing to use the website, you agree to cookies. Tell me more »
