Question 148282
Imagine that I am a passenger on train B. I have a stopwatch and a very
accurate clock too. I've got a cell phone and I'm in contact with 
someone at the station
I know the seed of train A and train B also.
I tell the station "Let me know exactly when train A passes the station"
They tell me "Train A just passed"
My clock tells me it's 12:25
Then my train, train B, passes the station.
My clock says it's 12:35. I start my stopwatch
10 minutes have passed, or {{{10/60}}}of an hour and since {{{d = r*t}}}
{{{d = 40*(10/60)}}}
{{{d = 40/6}}}mi
That's how far train A is from the station when I go past the station.
I know train A is {{{40/6}}} mi ahead of me, but when I stop the
stopwatch we will be side by side.
Let {{{t}}} = time from start to stop
{{{d}}} = the distance I have to go to meet train A
{{{d - 40/6}}} is the distance train A has to go to meet me
For A:
{{{d - (40/6) = 40t}}}
For B:
{{{d = 50t}}}
Substitute the 2nd equation into the 1st
{{{50t - (40/6) = 40t}}}
multiply both sides by {{{6}}}
{{{300t - 40 = 240t}}}
{{{60t = 40}}}
{{{t = 40/60}}} hr or {{{40}}} min
If I started my stopwatch at 12:35 PM, then the trains meet
at 1:15 PM answer
check answer:
{{{d = 50t}}}
{{{d = 50*(40/60)}}}
{{{d = 100/3}}} mi
Train A covers this distance (station to meeting) in 
{{{10/60 + 40/60 = 50/60}}} hr
{{{d[A] = r[A]*t}}}
{{{100/3 = 40*(50/60)}}}
{{{100 = 120*(5/6)}}}
{{{600 = 120*5}}}
{{{600 = 600}}}
OK