Question 967770
Today:  {{{m=5s}}}


Four years ago:  {{{(m-4)=9(s-4)}}}


Substitute for m.
{{{5s-4=9(s-4)}}}
{{{5s-4=9s-36}}}
{{{5s-9s=-36+4}}}
{{{-4s=-32}}}
{{{highlight(s=8)}}}