Question 1026476
since p(A)=a
and n(s)=s
Then p(A)=a/s
also,p(A')=1-p(A)
          =1-(a/s)
now,
p(A)+p(A')=(a/s)+1-(a/s)
      =(a/s)-(a/s)+1
     =1
p(A)+p(A')=1
Hope this helps?