Parallel Conductance Equation
$$\text{Let Conductance} = G$$
$$\text{Let Equilibrium Potential} = E$$
$$\text{Reverse Membrane Potential}\ (V_m) = \frac{(G_{Na}*E_{Na}) + (G_K*E_K)+(G_{Cl}*E_{Cl})}{G_{Na}+G_K+G_{Cl}}$$
 Use Common Ions 
 Sodium   Potassium   Chloride 
 Sodium   Potassium   Chloride