Question 799445
Let {{{ t }}} = time for boat to go upstream
{{{ 5 - t }}} = time to go downstream
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Equation for going upstream:
{{{ d = 8t }}}
Equation for going downstream:
{{{ d = 12*( 5 - t ) }}}
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By substitution:
{{{ 8t = 12*( 5 - t ) }}}
{{{ 8t = 60 - 12t }}}
{{{ 20t = 60 }}}
{{{ t = 3 }}}
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You should turn back in 3 hrs
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{{{ d = 8t }}}
{{{ d = 8*3 }}}
{{{ d = 24 }}}
You'll be 24 miles from the resort
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check:
{{{ d = 12*( 5 - 3 ) }}}
{{{ d = 12*2 }}}
{{{ d = 24 }}}
OK