Let R be an equivalence relation on the set $A= \{1,2,3,4,5\}$ given by R= {(x, y):2 divides (x - y)}. Then equivalence class of 3 is:

$\{1,3,5\}$

$A= \{1,2,3,4,5\}$  R= {(x, y):2 divides (x - y)}

for any $x∈A$

$(x-x)=0$ (divisible by 2)

$⇒(x,x)∈R$ for all $x∈A$  (Reflexive relation)

so for 3 → its equivalence relation is $\{1,3,5\}$

(1-3)(3-3)(5-3) all divisible by 2