Question 1140918
Given problem is to prove {{{(B-A)U(C-A)=(BUC)-A}}},

	Let {{{x}}} be ∈ {{{(B - A) U (C - A)}}} 


	=> {{{x}}} ∈ {{{(B - A)}}} or {{{x}}} ∈ {{{(C - A)}}}

	= ({{{x}}} ∈ {{{B}}} and {{{x}}} ∉ {{{A}}}) or ({{{x}}} ∈ {{{C}}} and {{{x}}} ∉ {{{A}}})

	= ({{{x}}} ∈ {{{B}}} or {{{x}}} ∈ {{{C}}}) and ({{{x}}} ∉ {{{A}}})

	= ({{{x}}} ∈ {{{B U C }}}) and ({{{x}}} ∉ {{{A}}})

	= {{{x}}} ∈ {{{(B U C) - A}}}

Hence proved {{{(B - A) U (C - A) = (B U C) - A}}}