[defang01]

I have problem solving the following question.

At 373 K, Kc = 4.5X10^9 L/mol for the reaction CO (g) + Cl2 (g) = COCl2 (g)  Equal moles of CO and Cl2 react at 373 K. If the total pressure at equilibrium is 5.0 atm, calculate the equilibrium partial pressure of all the gases (CO, Cl2, COCl2).

First, I calculated the Kp by Kp = Kc (RT)^n and I got 9.89 X 10^-5
Then, I did CO + Cl2 = COCl2
                   x        x        0
                  -y       -y       +y
(x-y)+(x-y)+y = 5; y=2x-5
Then, 9.89x10^-9 = (y) / (x-y)^2 (I substituted y for 2x-5).  However, I have trouble solving for x. Could anyone tell me what I did wrong?  Thanks!