text: ```Question 549899
  The 1st train has a head start of
  {{{ 80*3 = 240 }}} mi
  Start a stopwatch when the 2nd train leaves
  Let {{{d}}} = distance 2nd train goes until they meet
  Let {{{t}}} = time on stopwatch when they meet
  ---------------
  2nd train:
  {{{ d = 100t }}}
  1st train:
  {{{ d - 240 = 80t }}}
  -----------------
  By substitution,
  {{{ 100t - 240 = 80t }}}
  {{{ 20t = 240 }}}
  {{{ t = 12 }}}
  This is 12 hrs after the 2nd train leaves at 6 PM + 3 = 9 PM
  The 2nd train catches up with the 1st train at 9 AM the next day
  -----------------