Answer
{$-7,5$}
Work Step by Step
Using the rules of factoring trinomials to factor, we obtain:
$a^{2}+2a-35=0$
$a^{2}+7a-5a-35=0$
$a(a+7)-5(a+7)=0$
$(a+7)(a-5)=0$
$(a+7)=0$ or $(a-5)=0$
$a=-7$ or $a=5$
Therefore, the solution set is {$-7,5$}.