Question 1091184
In words:
[ mi/min with sail ] x [ min sailed ] + [ mi/min with motor ] x [ min with motor ] = [ distance traveled ]
Let {{{ x }}} = minutes traveled with sail
Let {{{ y }}} = minutes traveled with motor
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{{{ 9/60 = 3/20 }}} mi/min
{{{ 14/60 = 7/30 }}} mi/min
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{{{ (3/20)*x + (7/30)*y = 5 }}}
Multiply both sides by {{{ 60 }}}
{{{ 9x + 14y = 300 }}}
{{{ 14y = -9x + 300 }}}
{{{ y = -(9/14)*x + 150/7 }}}
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Here's the plot:
{{{ graph( 400,400, -5, 50, -5, 50, -(9/14)*x + 150/7 ) }}}