Circuit: V1 (through R1) and V2 (through R2) both feed into common node A; R3 connects node A back to the shared ground/return. Kirchhoff's Current Law (KCL) at node A: current in from V1's branch + current in from V2's branch = current out through R3. Combined with Ohm's law on each branch (I=(V_source−V_A)/R), this gives one equation in one unknown (V_A), solvable directly — this is the same result Millman's theorem gives as a shortcut: V_A = (V1/R1 + V2/R2) ÷ (1/R1 + 1/R2 + 1/R3). A negative current means the actual current flows opposite to the assumed "into node A" reference direction shown in the diagram — that's a normal, correct outcome, not an error.