When should I use KUN, PER and PRI?

Explanation

KUN indicates company and means "with, not without, together, not separate, not scattered".

PER indicates a means, tool or object, by the help of which some action occurs, or that is used to achieve some goal or result. It means "with, through, by means of, with the help of"

PRI indicates a subject, or something that an action deals with or relates to, and means 'about, concerning, in relation to, on the subject of.'

Examples

Dividi biciklon kun sia najbaro. - Share a bicycle with one's neighbor.
Dudek dividite per kvar egalas kvin. - Twenty divided by four equals five.

Pri tio mi ne volas disputi. - I don't want to argue about that.
Pli bone ne disputi kun li pri tio. - Better not argue with him about that.

Oni vivas ne kun mono, sed kun persono. - You don't live with money, but with a person.
Per mono ne ĉion eblas aĉeti. - Not everything can be bought with money.

Ŝi kun sia edzo veturis per trajno. - She travelled by train with her husband.
Li parolis kun sia amikino pri Esperanto per telefono. - He talked with his friend about Esperanto on the phone.

Exercises

Level 1 Level 2