Relations And Functions

Let R be a relation from Q to Q defined by R = {(a,b): a,b ∈ Q and
a – b ∈ Z}. Show that
(i) (a,a) ∈ R for all a ∈ Q
(ii) (a,b) ∈ R implies that (b, a) ∈ R
(iii) (a,b) ∈ R and (b,c) ∈ R implies that (a,c) ∈R