Let P, A, B, C, D be points on a plane such that PA=9, PB=19, PC=9, PD=5, ∠APB=120∘, ∠BPC=45∘, ∠CPD=60∘, and ∠DPA=135∘. Let G1, G2, G3, and G4 be the centroids of triangles PAB, PBC, PCD, PDA. [G1G2G3G4] can be expressed as ab+cd. Find a+b+c+d.2022 CCA Math Bonanza Individual Round #15