Question 1150851
Charles is four times as old as his daughter Nina.
{{{Charles=4Nina}}}......eq.1

Eight years ago he was ten times as old as Nina.

{{{Charles-8=10(Nina-8)}}}

{{{Charles-8=10Nina-80}}}
{{{Charles=10Nina-80+8}}}
{{{Charles=10Nina-72}}}.......eq.2

from eq.1 and eq.2

{{{4Nina=10Nina-72}}}

{{{72=10Nina-4Nina}}}

{{{72=6Nina}}}

{{{Nina=72/6}}}

{{{Nina=12}}}..........Nina is {{{12}}} years old today

then
{{{Charles=4Nina}}}......eq.1
{{{Charles=4*12}}}
{{{Charles=48}}}......Charles is {{{48}}} years old today