When N2O5 (g) is heated it dissociates into N2O3 (g) and O2(g) according to the following reaction: N2O5(g) <--> N2O3(g) + O2(g) Kc= 7.75 at a given temperature. The N2O3(g) dissociates to give N2O(g) and O2(g) according the following reaction:
N2O3(g) <--> N2O(g) + O2 (g) Kc= 4.00 at the same temperature. When 4.00 mol of N2O5(g) is heated in a 1.00-L reaction vessel to this temperature, the concentration of O2(g) at equilibrium is 4.50 mol/L

a.) Find the concentration of N2O5 in the equilibrium system.
b.) Find the concentration of N2O in the equilibrium system.
c.) Find the concentration of N2O3 in the equilibrium system.