(a) The universal set is \(\mathcal E=\{x:1\lt x\lt 20,\ x\in\mathbb Z\}\). The set \(A\) contains the multiples of 3 and the set \(B\) contains the multiples of 4.

(i) Find \(n(A)\).

(ii) Find \(n(A\cap B)\).

(b) On the Venn diagram, draw sets \(P\), \(Q\) and \(R\) such that \(P\subset Q\) and \(Q\cap R=\varnothing\).

(c) For each shaded Venn diagram, describe the shaded region in set notation.