Question 1010572
Plot population {{{ p }}} on the vertical axis
Plot time {{{ t }}} in years on the horizontal axis
You are given two points on a straight line:
( -5, 1600 )
( 0, 1000 )
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Use the general point-slope formula to 
find the equation
{{{ ( p - 1000 ) / ( t - 0 ) = ( 1600 - 1000 ) / ( -5 - 0 ) }}}
{{{ ( p - 1000 ) / t = 600 / (-5) }}}
{{{ ( p - 1000 ) / t = -120 }}}
{{{ p - 1000 = -120t }}}
{{{ p = -120t + 1000 }}}
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{{{ 300 = -120t + 1000 }}}
{{{ 120t = 1000 - 300 }}}
{{{ 120t = 700 }}}
{{{ t = 5.833 }}}
In 5 years and 10 months, population drops below 300
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check:
( -5,1600 )
{{{ p = -120t + 1000 }}}
{{{ 1600 = -120*(-5) + 1000 }}}
{{{ 1600 = 600 + 1000 }}}
{{{ 1600 = 1600 }}}
OK
( 0, 1000 )
{{{ p = -120t + 1000 }}}
{{{ 1000 = -120*0 + 1000 }}}
{{{ 1000 = 1000 }}}
OK
( 5.8333, 300 )
{{{ p = -120t + 1000 }}}
{{{ 300 = -120*5.8333 + 1000 }}}
{{{ 300 = -700 + 1000 }}}
{{{ 300 = 300 }}}
OK