PLEASE HELP!!! chem test in 2 days!!!!!!!!!!!!!!!!!!?

A student was studying the reaction, SO2Cl2(g)SO2(g) + Cl2(g). The value of Kp for the system is 12.5 when the temperature is 565 K. A reactor vessel was charged with enough SO2Cl2(g) to give it a pressure of 1.200 atm at 25.0 �C. The temperature of the sealed system was increased to 565 K and the system left undisturbed so it could come to equilibrium. Calculate what the total pressure should be, in atmospheres, at equilibrium.