You need to write in role when responding to the exam task. Clearly, your opening sentences will depend on the question, but here's a possible way of getting in to the question:
Dear Sir (or whatever - a name is usually given)
From my research into music magazines, I have come to understand that the genre is clearly under threat from the vast array of information and music, legal or otherwise, that can be found easily on the .Internet, but I have looked at how magazines appeal to their target audiences.
And so on, depending on the question...