I encountered this problem and did not know how to solve it:
I graphed it out - making a point for each vertice. I then decided there must be a 3 because when $x=0$ then $y=3$. But, according to that logic, it should be answer c - because when $y=0$ then $x=3$. But, that is not the answer.
Where did I go wrong, and how should I go about solving this problem when I am not given an answer key?