Sodium Sulfide (Na2S)
Iron (III) Nitrate (Fe(NO3)3
Na2S (aq) + Fe(NO3)3 → 2Na+ + S2- + Fe2+ + 3NO3
As long as the charges are equivalent from both sides of the equation then you are done.
We know the charges are equivalent because Na = +, S = 2+, Fe = 2-, and NO3 = -