Question 108127
If {{{Ann=x-years-old}}} => 

And {{{Mary=y-years-old}}}

Then:

{{{x = y+6}}}...because Ann is {{{6}}} years older than Mary.
and
{{{x=2y-6}}}....She is also {{{twice}}} as old as Mary was when {{{Ann- was- as -old- as- Mary- is -now}}}


use these two equations above to solve the problem:


since the left sides of the equations above are equal, and then right sides must be equal too:

{{{y+6 = 2y-6}}}

{{{y + 6 = 2y-6 }}}….move {{{y }}}

{{{6 +6= 2y-y}}}

{{{y = 12}}}……….. Mary is{{{12-years-old}}}
 Then ………………......Ann is {{{18-years-old}}} 


check:

Ann is {{{18}}}, Mary is {{{12}}}      => Ann is {{{6}}} years older then Mary or{{{12 +6=18}}}

When {{{Ann}}} was as old as {{{Mary}}} is now, means it was before {{{6}}} 

years 

and before {{{6}}} years Ann was {{{18-6=12}}} and Mary was {{{12-6 = 6}}}

When Ann was {{{12}}}, she was twice as old as Mary ({{{2*6=12}}}).