Slowly being introduced to Propositional Logic...did I get this right?

Question

I want to make sure I'm getting the concept down. The question is asking

(P'-->Q') [AND] Q [AND] (P-->R) --> R

Here is what I did:

1. (P'-->Q') = (Hypothesis)
2. Q = (Hypothesis)
3. (P-->R) = (Hypothesis)
4. P = (1,2, modus tollens)
5. R = (3,4, modus ponens)

Is that correct? What I'm struggling to understand is which statement I should prove first and how I know if I'm including enough steps and all that and I just wanted to see if I got a good grasp of this concept. I will obviously do more examples but I just want to see if I'm headed in the right direction.