I think answer is 4
Let us take an example as R= {(10,1),(20,2)} and S={(2,30),(3,40)}
I) R⟗S= {(20, 2,30)}. So π A, B R⟗S = {(20,2)}
II) π B (S) ={(2),(3)}. So R⟗π B (S) = {(20,2)}
III) π A (R) X π B (S) ={10,20} X {2,3} ={(10,2),(10,3),(20,2),(20,3)}
R ∩ π A (R) X π B (S)={(20,2)}
IV) R X S = {(10,1,2,30),(10,1,3,40),(20,2,2,30),(20,2,3,40)}
π A, R.B R X S ={(10,2),(10,3),(20,2),(20,3)}