Let n(U)=700,n(A)=200,n(B)=300 and n(A∩B)=100 then n(Ac∩Bc)=
n(Ac∩Bc)=n[(A∪B)c]=n(U)−n(A∪B) =n(U)−[n(A)+n(B)−n(A∩B)] =700−[200+300−100]=300