Only you can answer this.
Maybe it's "And Then There Were None."
I don't know what your teacher thinks Agatha Christie's masterpiece was, but this site may help you. http://en.wikipedia.org/wiki/Agatha_Christie
AP US History
Yes, you're right.
n = 4n - 6 6 = 3n 2 = n
Princess Anna -- at least Prof Reiny showed the student how he got the right answer.
Names could be indirect objects and they can also be direct objects. In this sentence Joe is an indirect object: I gave Joe a present. In this sentence Joe is a direct object. Julie kissed Joe.