Question 1190170
mother m
daughter d
{{{system(m-6=5(d-6),d=m/3)}}}


{{{m-6=5(m/3-6)}}}

-
{{{3(m-6)=15(m/3-6)}}}

{{{3m-18=5m-90}}}

{{{-18+90=2m}}}

{{{m=45-9}}}

{{{highlight(m=36)}}}

Agnes is {{{1/3}}} of that, so she is {{{highlight(highlight(12))}}}.