Question 955619
{{{n/d=2/3}}};
{{{(n-4)/(d+3)=1/3}}}


The changed form becomes {{{3(n-4)=d+3}}}
{{{3n-12=d+3}}}
{{{3n=d+3+12}}}
{{{highlight_green(3n=d+15)}}}


The original fraction gives {{{n=2d/3}}}.


Substitute.
{{{3(2d/3)=d+15}}}
{{{2d=d+15}}}
{{{highlight(d=15)}}}, the value to be answered.