Question 419207
The key is to find out how much of a head start train A has.
The difference between 4:20 and 4:50 is {{{.5}}} hrs
So, A's head start is {{{d1 = 40*.5}}}
{{{d1 = 20}}} mi
Another key is the fact they will be traveling for the same
amount of time after B passes station  
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Start a stopwatch when B leaves station
train A:
{{{ d - 20 = 40t }}}
train B:
{{{d = 44t }}}
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By substitution:
{{{ 44t - 20 = 40t }}}
{{{ 4t = 20 }}}
{{{ t = 5 }}} 
This says that {{{5}}} hrs after B passes station, B catches A
4:50 AM + 5 = 9:50 AM answer
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check answer
{{{d = 44t}}}
{{{d = 44*5}}}
{{{d = 220}}} mi
This is the distance B goes from station
Train A went this distance  in {{{5 + .5 = 5.5}}} hrs
{{{220 = 40*5.5}}}
{{{220 = 220}}}
OK