Answer
{$11,15$}
Work Step by Step
Using the rules for the factoring of trinomials, we obtain:
$n^{2}-26n+165=0$
$n^{2}-11n-15n+165=0$
$n(n-11)-15(n-11)=0$
$(n-11)(n-15)=0$
$(n-11)=0$ and $(n-15)=0$
$n=11$ and $n=15$
Therefore, the solution set is {$11,15$}.