Calculation of Equilibrium Constant

Consider the following equilibrium reaction at a given temperature:

A(g) + B(g) ↔ C(g) + D(g)

At equilibrium, the concentrations of the reactants and products are found to be as follows: [A] = 0.5 M, [B] = 0.5 M, [C] = 0.2 M, [D] = 0.2 M.

Determine the equilibrium constant (K) for the reaction at this temperature.