What is the active or passive voice of Maddy is considered one of the best writers in school ?

The sentence is in PASSIVE VOICE.

Explanation:

When subject of the sentence performs the actions, then the sentence is in active voice.  When the subject of the sentence is the receiver of the action, then the sentence is in passive voice

In the above sentence:  

Maddy does not perform any action, i.e. Maddy IS NOT PERFORMING THE ACTION OF WRITING.  Rather, Maddy IS ACTED UPON AS ONE OF THE BEST WRITERS; hence, Maddy is the receiver of the action.  Hence the sentence is in passive voice.

write a five paragraph essay, you were taught to have three body paragraphs. a university essay is more flexible than that, depending on its length and on what it is trying to say. a short university essay may have three body paragraphs, but it may have more.

the sentence that avoid faulty coordination is:

culture, which is well represented in philadelphia, plays a major role including theatre, music, and the visual arts.  

faulty coordination occurs when the writer gives equal importance two different ideas (clauses) which in fact are not equivalent. in order to correct a misplaced clause or idea, the writer can place less important or emphatic ideas in a relative clause as in the previous sentence.