Show that the relation R in the set A={x belongs to z : 0 ≤ x ≤ 12} is

This question was asked in Ex 1.1, 14

Show that the relation R in the set A={x belongs to z : 0 ≤ x ≤ 12} is given by
a). R = {(a,b) : |a-b| is multiple of 4}
b). R = {(a,b) : a = b}