Question 620733
Say they are {{{ d }}} miles apart
Let the time for them to meet  = {{{t}}}
They approach each other at the sum of their speeds
{{{ d = ( 50 + 30 )*t }}}
{{{ t = d/80 }}}
For the 50 mi/hr train:
It's distance is {{{ 50*(d/80 ) }}}
For the 30 mi/hr train:
It's distance is {{{ 30*( d/80 ) }}}
{{{ 50*( d/80 ) + 30*( d/80 ) = d }}}
{{{ (5/8)*d + (3/8)*d = d }}}
{{{ 5/8*d - 3/8*d = 1/4*d }}} 
The 50 mi/hr train goes 1/4 of the distance between them further