Question 783172
Think of one car as standing still and the other as
traveling at the difference of their speeds.
the distance from the moving car and the stationary car
is {{{ 84 }}} mi
Let {{{ t }}} = time in hours when the distance between 
the moving car and the stationary car
is {{{ 84 }}} mi
----------------------
{{{ 84 = ( 55 - 41 )*t }}}
{{{ t = 84/14 }}}
{{{ t = 42/7 }}}
{{{ t = 6 }}}
In 6 hrs they will be 84 mi apart