# Find the equilibrium constant

In a container with volume 4 litres we have 2 moles $\ce{COCl2}$ and 4 moles $\ce{Cl2}$. Equilibrium is achieved when 60 % of the reactant $\ce{COCl2}$ is wasted 60 %. What is the equilibrium constant $\ce{CO + Cl2 <=> COCl2}$?
In my book it is explained the solution. I understand it when it says that $\ce{PCl5}$ is the substance that is wasted, but after finding the concentration of each substance to find the constant it uses the formula: $k=I$ understand that we get the concentration of $\ce{Cl2}$, $\ce{COCl2}$, but then when he finds the constant it divides $[\ce{CO}]\cdot[\ce{Cl2}]$ with $[\ce{COCl2}]$.

But I think that they should divide $[\ce{COCl2}]$ with $[\ce{CO}]\cdot[\ce{Cl2}]$.