Why can't I get correct reactive and real power in what seems to be easy task
The angle of 30 degrees associated with your voltage supply is a complete red herring. Your voltage supply is 100 volts period because your load cares not one bit about the phase angle. All the load sees is 100 volts RMS.

So, without the safety net of a calculator, I can see the load impedance is 5 ohm and this takes 20 amps. That 20 amps flows through the resistive element of the load of 3 ohms and therefore dissipates 400 x 3 watts.