Question 1102066
{{{system(f+c=36,f+7=4(c+7))}}}


{{{f+7=4c+28}}}
{{{f=4c+21}}}
{{{4c+21+c=36}}}
{{{5c=36-21}}}
{{{5c=15}}}
{{{highlight(c=3)}}}--------son
-
{{{f=12+21}}}
{{{highlight(f=33)}}}------father