<PRE><B>Question 1045602</B>
1 hr  = {{{ 60 }}} min
{{{ 60 - 20 = 40 }}}
So, the 2nd of the drive must take {{{ 40/60=2/3 }}} hr
to arrive on time
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For 1st part of trip:
{{{ d = 30*(20/60) }}}
{{{ d = 30*(1/3) }}}
{{{ d = 10 }}} mi
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{{{ 60 - 10 = 50 }}}
The distance for 2nd part of trip is {{{ 50 }}} mi
Let {{{ s }}} = the speed for 2nd part of trip
{{{ 50 = s*(2/3) }}}
{{{ s = (3/2)*50 }}}
{{{ s = 75 }}}
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You must go 75 mi/hr for the 2nd part of the trip
to arrve on time</PRE>