Equivalence relations-Discrete Math Here is an equivalence relation R={ (x,y) | x-y is an integer} 
My question is: what is the equivalence class of 1 for this equivalence relation? 
Can say indicate the equivalence class of 1 as [(1)] = { (x,y), x-y=  }  
I am confused about how to write the right hand side? can someone help me? 

The equivalence class of $1$ is $\mathbb{Z}$.
Show that $x-1$ is an integer if and only if $x$ is an integer.
