The super heated steam at pressure=P1=500kpa and Tempwerature(T1)= 300 C
therefore, The enthalpy at initial state=H1=mxh1=8x(3064.6)=24516.8 KJ
If it is cooled at same pressure , steam becomes saturated at temp (T2)=152 C.
At P2=500kPa, hf=640.09 kJ/Kg, hg=2748.01 kJ/Kg
The enthalpy of saturated steam (H2) =mxh2=m(hg)=8x2748.01=21984.08 kJ.
If 70% of steam is condensed at state-3 , dryness fraction at state-3 is X=0.3.
Therefore enthalpy of steam at state -3 is given by