075. Solving a chemistry problem

11. For the gas reaction A=B C, it is known that the equilibrium depth of the reaction is 0.78 mol, and the equilibrium pressure is 1.2 atm. The initial amounts of starting substances are equal to the stoichiometric coefficients; there is no reaction product at the initial moment.
Need to find:
1) equilibrium mole fractions of all reaction participants;
2) the value of the equilibrium constant.