Your answer for B is correct.
A. Factorise completely:
(a) 18x^2 – 24xy + 8y^2
the answer i get is 2(3x+y)^2
but the answer given is 2(3x + 2y)^2
B.Factorise the following:
(a) (x – 4)(x + 1) + 4a – ax
the answer i get is (x-4)(x+1-a)
but the answer given is (x-4)(x-1-a)