On https://askubuntu.com/a/1026404/711310, I got two upvotes and zero downvotes, but I gained 35 reputation from it. How did this happen?
You got another 15 rep because your answer was accepted. See https://askubuntu.com/help/whats-reputation for details about reputation. The relevant bit here is:
You gain reputation when:
[ . . . ]
answer is marked “accepted”: +15 (+2 to acceptor)
Also see https://askubuntu.com/reputation
It is a personal text based aggregated view of all your rep.