A(g)+ B(g) <---> C(g) + D(g)

Kc= 144. If .4 mol of A and B are placed in a 2 Liter container, what will be the concentration of C at equilibrium?

I said the concentration of A= .2 because (.4/2=.2)
and because 1 mol of A = 1 mol of C,

the concentration of C also = .2
But the answer was .185. What did I do wrong?

See your later post. I worked the problem after posting the response to your later post and the answer is, indeed, 0.185 M.