Question 850129
Say your father was 30 when you were born
The difference in your ages will always be 30 years
Add {{{ x }}} years to both your ages after you were born
{{{ ( 0 + x ) / ( 30 + x ) }}} is the ratio of your ages in {{{ x }}} yrs
{{{ ( 0 + x ) / ( 30 + x ) = 1/2 }}} ( you are 1/2 your father's age )
Multiply both sides by {{{ 2*( 30 + x ) }}}
{{{ 2x = 30 + x }}}
{{{ x = 30 }}}
---------------
So when your father is {{{ 30 + 30 = 60 }}},
you will be {{{ 0 + 30 = 30 }}} which is half
---------------
Try this with your father being , say 37 when 
you were born- to see if you get it