an equivalence relation is a relation that satisfies certain properties, particularly, 3 properties.

see any or all of the following thread for the properties you need to check and how to use them

http://www.mathhelpforum.com/math-he...relations.html

http://www.mathhelpforum.com/math-he...nce-class.html

http://www.mathhelpforum.com/math-he...uivalence.html

http://www.mathhelpforum.com/math-he...-relation.html

http://www.mathhelpforum.com/math-he...relations.html

hope those help