Equilibrium Constant Calculation

In a closed system at equilibrium, the following reaction is established:

A(g) + B(g) ⇌ C(g) + D(g)

At a certain temperature, the concentrations of the reactants and products are as follows:

[A] = 0.5 M, [B] = 0.5 M, [C] = 0.2 M, [D] = 0.2 M

What is the equilibrium constant (K_c) for this reaction at the given temperature?