(A) Prove the Following Statement Using the Element Method for Proving

Essay

(a) Prove the following statement using the element method for proving that a set equals the empty set: For all sets $A$ and $B , A \cap ( B - A ) = \emptyset$ .
(b) Use the properties in Theorem $6.2 .2$ to prove the statement in part (a). Be sure to give a reason for every step.