ada yang bisa ngasih tau caranya?? tolong bantu jwb yaa;;)

6.) F = {A, B, C, D}, {A, B, D, C}, {B, A, C, D}, {B, A, D, C}, {C, A, B, D}, {D, A, B, C}, {C, B, A, D}, {D, B, A, C}, {C, D, A, B}, {D, C, A, B}, {C, D, B, A}, {D, C, B, A} ⇒ n(F) = 12
     n (S) = 4! = 1 × 2 × 3 × 4 = 24
     P(F) = 12/24 = 1/2