> 
> Let $X=\{0,1,2,...,10\}.$ Define the relation $R$ on $X$ by:
>  for all $a,b$ in $X$, $a\mathrel{R}b$ if and only if $a+b=10$
> 
> 
> is $R$ reflexive? symmetric? transitive?
> 
> 
> 

$a\mathrel{R}a$  

$a+a=10$  

$2a=10$  

$a=5$

Im confused, is that consider as reflexive?