Finding the equlibrium constant, Kc?

What is the equilibrium constant, Kc, for an equilibrium mixture for the reaction 2BrCl3(g) ⇌ Br2(g) + 3Cl2(g) that was found to contain 1.3 mol BrCl3, 2.0 mol Br2 and 6.3 mol Cl2 in a 4.0-L vessel?