Evaluate the flux of the vector field F = <3x, x^2 + y, e^(xy) - 2z> across the surface of the closed cylinder which can be expressed as a union of two surfaces A and B. Surface A is given by A = {(x, y, z) | x^2 + z^2 = 9, -5 ≤ y ≤ 5}, and surface B is given by B = {(x, y, z) | x^2 + y^2 ≤ 9, y = ±5}.