Translation:He would give me a present if I got the answer wrong.
Hi YuMoises! Maybe they would accept it if you wrote if my answer was wrong"... but they might not because they are using "errar" as a verb (more or less close to the verb to err* in English), and I imagine they want something to take its place in English (since to err isn't really used in English for missing an answer/getting an answer wrong)--and that why they are using the verb to get (wrong).
In short, errar = to miss, to err, to get wrong, to make a mistake
A closer translation of your sentence would be: "Ele me daria um presente se minha resposta estivesse errada". See, it refers to the answer being wrong, as opposed to me getting it wrong. I hope it helps! =]
I agree completely! I put 'He would give me a present if I were to miss the answer.', and 'were to miss' was marked incorrect. Everything that I could study says that the past (imperfect) subjunctive puts the indication of something that might or might not happen on the verb. The translation above puts in in the word 'if' only and the verb is straight up 'wrong' or 'miss'.