Question

The dual statement of A-(B union. c)=(A-B) union (A-C) is _____. (It is a set mathematics)

Answer 1

incorrect(if that's what you're asking)
its is A-(B union C)=(A-B) intersection (A-C)

Answer 2

suppose  A={1,2,3,4,5}        B={2,3,4,5,6}       C ={3,4,5,6,7,8,9}
  Solving LHS :
Therefore   A-(B∪C)⇒ (B∪C) = {2,3,4,5,6,7,8,9} &   A= {1,2,3,4,5}
Therefore   A-(B∪C)⇒ {1}
 Now solving RHS :
 Therefore  (A-B) ∪ (A-C) ⇒(A-B) = {1}  &  (B-C) = {1,2}
Therefore  (A-B) ∪ (A-C) ⇒{1,2}