For each of the following arguments, it is possible to provide a formal proof of validity by validly inferring just three statements. Writing these out, carefully and accurately, will strengthen your command of the rules of inference, a needed preparation for the construction of proofs that are more extended and more complex.

(P₁): (P ⊃ Q) ⋅ (Q ⊃ P)
(P₂): R ⊃ S
(P₃): P ꓦ R
∴ Q ⊃ S