救救我 ><

糖果candy

sets~~
prove :
A n ( B - C ) = ( A n B ) - (A n C)

做不到

darksider

A n (B-C) = A n ( BnC').... definition
          = A n B n C'.... associative law
          = (AnBnC') u (AnBnA')
          = (AnB)n (A'uC')... distributive law (reverse, fyi)
          = (AnB)n (AnC)'... de morgan's law
          = (AnB)-(AnC) ... definition