Why is "but" used here? Both sentences are positive.
Perhaps the person making the statement believes that intelligence comes with age, so sees it as a contradiction that the person is both young and smart.
See Qup, QIp, 'ej moH by 'el yenqovIq taQ.
"Mara is young but smart" should work, too. Isn't it? Or is there a detail I am missing?
In fact that is even accepted as a best translation. Did you get marked wrong? Is it possible you had some other error in your sentence?
Yes, it was marked wrong. I am quite sure, that everything was correct, but maybe I will see the sentence again to be sure.
If it happens again take a screen shot and report it as "my answer should have been accepted". Both things give us details we can show the programmers.
Ok, thank you. I'll do it that way. :-)