"Their concert has had a big audience."
Translation:Concertul lor a avut o mare audiență.
It is not like in english were you must put the adjective in front of the substantive. You should work more on this. It is ok to say: Am un mare câine. But is also more ok to say: Am un câine mare. In this case is more than ok that the preposition can be translated like I did: Concertul lor a avut o audiență mare.