the answer is finis.
He finis let course à treize heures quarante-cinq.
Meaning: I finish class at one forty-five.
Of you were to use finissons and you translated the sentences you would have still gotten the same meaning but in French just like English there are some rules we have to follow and in the conjugation of er,ir and re verbs there are rules.
Since finir is under ir verbs I am going to emphasize on the ir verbs. In conjugating the regular ir verbs, je takes is.
tu takes is.
il and elle take it.
nous takes issons.
vous takes issez.
ils and elles take issent.
Making finis the appropriate verbs for the sentence.
And as for part and arrive they do not fit into the passage correctly.
If you want to use part then the sentence must be: Je pars le cours à treize heures quarante-cinq. and to use arrive.
It is supposed to be: J'arrive le cours à treize heures quarante-cinq.
