Solve ∂^2z/∂x∂y+∂z/∂x-∂z/∂y=z+xy

Solve ∂^2z/∂x∂y+∂z/∂x-∂z/∂y=z+xy
solve s+p-q=z+xy
Solve (D^2+D-D'-1)z=xy