Because the formation constant is so large we can say that the reaction has gone to completion.
An ICE table is not applicable in this case. It is just a reacting masses problem.
From the equation you can see that 1 mole of
This means that 0.15 mol require 4 x 0.15 = 0.6 moles.
However, we are told we only have 1L of a 0.5M solution which = 0.5 moles.
0.5 moles of
This means that the number of moles of
So we can say: