It’s „cui bono“ because it’s using dative case i.e. „whom is the favor“.
Declination of the Latin relative pronoun „qui“ is the following for the masculine genus:
qui
cuius
cui
quem
quo
Sorry for being a grammar nazi.
It’s „cui bono“ because it’s using dative case i.e. „whom is the favor“.
Declination of the Latin relative pronoun „qui“ is the following for the masculine genus:
qui
cuius
cui
quem
quo
Sorry for being a grammar nazi.