Hello Rahul.

Relation is said to be equivalent if it is symmetric, reflexive, and transitive for all elements present within the set solving that certain relation with other elements.

Equivalence class papers two such numbers which follow the equivalence condition. As the numbers are in relation with each other so, if three equivalent classes are in relation with the same set A, then it's obvious that the three equivalence classes are also in relation with each other in the same manner.