A square lawn has side (7p+3) metres. A smaller square garden of side (7p−3) metres is removed from its centre, leaving a walkway of uniform width all around.
(i) Write an algebraic expression for the area of the walkway in terms of p.
(ii) Factorise the expression obtained in part (i).
(iii) If p=2, calculate the numerical value of the area of the walkway.