If x + y + xy = 8y + Z + YZ = 15z + X + ZX = 35, then x + y + Z + XYZ=______ .

If x + y + xy = 8y + Z + YZ = 15z + X + ZX = 35, then x + y + Z + XYZ=______ .

∵ x + y + xy = 8, ∵ x + y + XY + 1 = 8 + 1, ∵ x + y + XY + 1 = 8 + 1, ∵ (x + 1) (y + 1) = 9, similarly, (y + 1) (Z + 1) = 16, (x + 1) (Z + 1) = 36, the solution is x = 72, y = 1, z = 7.