Question 341729
Simplify first.
{{{(a-6)/(a+15)=(2/2)(a/(a+3))}}}

{{{(a-6)/(a+15)=(a/(a+3))}}}
Multiply both sides by {{{(a+15)(a+3)}}}.
{{{(a-6)(a+3)=a(a+15)}}}
{{{a^2+3a-6a-18=a^2+15a}}}
{{{-3a-18=15a}}}
{{{18a=-18}}}
{{{highlight(a=-1)}}}