1. (P⋅G) ⊃ R
2. (R⋅S) ⊃ T
3. P⋅S
4. G v R
The conclusion is R v T.
I don't even know where to start and I can use basic rules of inference (MT, Disjunctive Syllogism, Dilemma, etc.) and replacement rules (Contraposition, Commutation, etc.).
Any help would be appreciated!