Question 1086277
Let {{{ d[1] }}} = Julie's head start in miles
Let {{{ t[1] }}} = Julie's head start in hrs
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Start a stop watch when Rob leaves
Let {{{ d }}} = distance in miles that Rob travels
until he catches up with Julie
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Rob's equation:
(1) {{{ d = 60*4 }}}
Julie's equation:
(2) {{{ d - d[1] = 45*4 }}}
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Plug (1) into (2)
(2) {{{ 240 - d[1] = 180 }}}
(2) {{{ d[1] = 60 }}}
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How much is Julie's head start in hours?
{{{ d[1] = 45*t[1] }}}
{{{ 60 = 45*t[1] }}}
{{{ t[1] = 4/3 }}} hrs
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Then Julies drives for {{{ 4 }}} more hrs, so
{{{ 4/3 + 4 = 5 + 1/3 }}}
Convert {{{ 1/3 }}} hrs to minutes
{{{ (1/3)*60 = 20 }}} min
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Julie had been driving for 5 hrs and 20 min 
when Rob caught up with her