What is the equilibrium value of [NH3], chemistry homework help

N2(g) + 3H2(g) <=====> 2NH3(g)nitrogegn gas and hydrogen gas are poured in a 1.0 litre vessel in a 1:3 ratio. The equilibrium constant for the reaction is 1.0x10^-4 and the equilibrium value of [h2(g)] is 0.12 mol/L. What is the equilibrium value of [NH3]?