four and five are nine?
Could you use "sυν" (plus) instead of "και"?
Συν yes. I think that translations in the same style would be:
Four plus five equals nine = τέσσερα συν πέντε ίσον εννέα
Four and five make/ are nine = τέσσερα και πέντε κάνουν εννέα
Should it not be plural κάνουν?
I almost wrote “Four plus nine equals five”. Math 101
four plus five is nine ?