This is the same problem. Remember, that it does not matter where you start, given a certain amount of material, you will always end up at the same equilibrium conditions. Therefore, we can just go back to the beginning of the last problem and set the molality of C to be 1.2 mole/kg instead of 0.2 and do it again. This is left as an excercise for the reader. I get the equilibrium molality of A is 0.37 moles/kg, for B it is 1.37 moles/kg and for C it is 2.26 moles/kg.