**The relation R = {(x, y)|x − y is an integer} is an equivalence relation on the
set of rational numbers.**

I'm kind of confused with this question and what it is asking me to do. In order to solve this, do I just take two arbitrary rational numbers and disprove that x-y is an integer? For example, 1/2 - 2/3 is not an integer. How does this tie in with an equivalence relation? 

Thanks in advance.