Let A and B be two sets then
A∪Bc∪Ac∩B=
Ac
Bc
ϕ
U
A∪Bc∪Ac∩B
=Ac∩Bc∪Ac∩B
=Ac∪Ac∩Ac∪B∩Bc∪Ac∩Bc∪B
=Ac∩Ac∪B∩Bc∩U
=Ac∩Ac∪ϕ∩U
=Ac∩Ac∩U=Ac∩U=Ac
or use venn diagram