Let A = {1, 2, 3, 4, 5} and a relation on it is $\mathrm{R}=\left\{\right(\mathrm{x},\mathrm{y})/\mathrm{x},\mathrm{y}\in \mathrm{A}\text{ and }\mathrm{x}+\mathrm{y}=5\}$ then R is 

Let $A=\left\{1,2,3,4,5\right\}$

And , $R=\left\{\left(x,y\right): x,y\in A and x+y=5\right\}$

R = {(1, 4), (2, 3), (3, 2), (4, 1)}

 So R is not reflective as $(1,1)\notin R$ also R is symmetric by definition and R is not transitive as 

$(1,4)\in \mathrm{R}$, $(4,1)\in \mathrm{R}\text{ but }(1,1)\notin \mathrm{R}$.