Question 669703
What is Lauren's head start in miles?
{{{ d[1] = 70*(1/2) }}}
{{{ d[1] = 35 }}} mi
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Start a stop watch when Jeff leaves
They will move apart for the same
amount of time {{{ t }}} until they are
440 mi apart
Let {{{ d }}} = the distance Jeff travels 
in time {{{ t }}}
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Jeff's equation:
{{{ d = 55t }}}
Lauren's equation:
{{{ 440 - d - 35 = 70t }}}
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Substitute (1) into (2)
{{{ 440 - 55t - 35 = 70t }}}
{{{ 125t = 405 }}}
{{{ t = 3.24 }}}
They can talk for 3 hrs 14 min 24 sec plus 1/2 hr
that is 3 hrs 44 min 24 sec
check:
{{{ d = 55t }}}
{{{ d = 55*3.24 }}}
{{{ d = 178.2}}}
and
{{{ 440 - d - 35 = 70t }}}
{{{ 440 - d - 35 = 70*3.24 }}}
{{{ 405 - d = 226.8 }}}
{{{ d = 405 - 226.8 }}}
{{{ d = 178.2 }}}
OK