If ${N_a} = \{ an:n \in N\} ,$ then ${N_3} \cap {N_4} = $

If $A = \{2, 3, 4, 8, 10\}, B = \{3, 4, 5, 10, 12\}, C = \{4, 5, 6, 12, 14\}$ then $(A \cap B) \cup (A \cap C)$ is equal to

Consider the following relations :

$(1) \,\,\,A – B = A – (A \cap B)$

$(2) \,\,\,A = (A \cap B) \cup (A – B)$

$(3) \,\,\,A – (B \cup C) = (A – B) \cup (A – C)$

which of these is/are correct

If $A=\{3,6,9,12,15,18,21\}, B=\{4,8,12,16,20\},$ $C=\{2,4,6,8,10,12,14,16\}, D=\{5,10,15,20\} ;$ find

$C-D$

Show that the following four conditions are equivalent:

$(i)A \subset B\,\,\,({\rm{ ii }})A – B = \phi \quad (iii)A \cup B = B\quad (iv)A \cap B = A$