Question 1149036
{{{s-3=7(m-3)}}}

{{{s-3=7m-21}}}

{{{s-7m=-21+3}}}

{{{7m-s=21-3}}}

{{{7m-s=18}}}




Susan now,  {{{7m-18}}}
Mercy now,  {{{m}}}


THREE YEARS AGO:
Susan, {{{7m-21}}}
Mercy, {{{m-3}}}