NH4HS(s)⇌NH3(g)+H2 S(g) the equilibrium Pressure at 25oC is 0.660 atm. what is K p for the reaction?

NH4HS(s)⇌NH3(g)+H2S(g)t = 0;    a mole           0              0teq.  ;     a-x                 x               xn = x + x =2x∵PGas =XGas ·PTotal  ⇒PNH3=12×0.66=0.33 atm PH2 S=12×0.66=0.33 atm  Now kp=PNH31PH2 S1=0.33×0.33