(a, a) ∈ R |a – a| =0 is even, which is true
R is reflexive,
a R b and b R c
⇒ |a – b| is even and |b – c| is even
⇒ (a- b) is even and b – c is even
⇒ (a- b) + (b – c) is even
⇒ (a- c) is even ⇒ |a – c| is even
⇒ a R c, hence R is transitive
since R is reflexive, symmetric and transitive
R is an equivalence relation.
|1 – 3| = 2, even, |1 – 5| = 4, even |3 – 5| = 2,
even hence all the elements of {1, 3, 5} are related to each other.
|2 – 4| = 2, even, hence all the elements {2,4} are related to each other.
|1-2| = 1, |3-2| = 1, |5-2| = 3, |1-4| = 3,
|3 – 4| = 1, |5 – 4| = 1, are all odd.
Therefore no elements of {1, 3, 5} are related to {2, 4}.