Question 560312
I can solve it the way I do this kind of problem
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I imagine that a stopwatch is started when the
2nd person, Bill, leaves. Then I need to know 
how much of a head start the 1st person, Dana, got.
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Dana's head start is
{{{ d[1] = 30*(1/3) }}} ( note that 20 min is 1/3 of an hour )
{{{ d[1] = 10 }}} mi
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Now when the stopwatch is started, they both will be 
traveling for the same amount of time, {{{t}}}, until they meet
Let {{{ d }}} = distance Bill travels in this time
Bill's equation:
(1) {{{ d = 50t }}}
Dana's equation:
(2) {{{ d - 10 = 30t }}} ( Dana has 10 mi less to travel )
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Substitute (1) into (2)
(2) {{{ 50t - 10 = 30t }}}
(2) {{{ 20t = 10 }}}
(2) {{{ t = .5 }}}
It will take him a half hour to catch her
check answer:
(1) {{{ d = 50t }}}
(1) {{{ d = 50*.5 }}}
(1) {{{ d = 25 }}}
and
(2) {{{ d - 10 = 30t }}} 
(2) {{{ d - 10 = 30*.5 }}}
(2) {{{ d = 15 + 10 }}}
(2) {{{ d = 25 }}}
This is the distance from home to where they meet
OK
The table would have {{{ d[1] }}}, their speeds, t, and {{{ d }}}