Q = K = [N2O4] / [NO2]^2 = 1.50 / (0.50)^2 = 6.00

Q = [N2O4] / [NO2]^2 = 1.33 / (0.67)^2 = 2.96

[NO2] = 0.50 M [N2O4] = 1.50 M

Since Q = 0.00, the reaction is not at equilibrium.