Work Step by Step
When we reverse the digits of $15$ we get $51$. This means that $15$ is not a palindromic number. $15$ is not an even number. A - the set of palindromic numbers B - the set of even numbers $15$ Belongs in neither A nor B; therefore, it belongs in the region that is outside of the circle for A as well as the circle for B: the $IV$ region.