Note that -4(5x) = 12 => -20x = 12, so that x = -3/5. The given equation is solveable, and the solution is -3/5. Asking whether -4(5x)=12 is "true" or "false" is pointless; this equation is conditionally true, with that truth hinging on x = -3/5. Similarly, -4(5x)=12 is not describable by "open."
