Question 1093831
Plot time in yrs on the horizontal axis
Plot value of the laptop on the vertical axis
Let {{{ x = 0 }}} be the time in yrs when he bought it
Use general point-slope formula
{{{ ( 805 - 1180 ) / ( 3 - 0 ) = ( y - 1180 ) / ( x - 0 ) }}}
{{{ ( -375 ) / 3 = ( y - 1180 ) / x }}}
{{{ -375x = 3y - 3540 }}}
{{{ 3y = -375x + 3540 }}}
{{{ y = -125x + 1180 }}}
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{{{ x = 7 }}}
{{{ y = -125*7 + 1180 }}}
{{{ y = -875 + 1180 }}}
{{{ y = 305 }}}
It will be worth $305 
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check:
Does equation go through ( 3, 805 ) ?
{{{ y = -125x + 1180 }}}
{{{ 805 = -125*3 + 1180 }}}
{{{ 805 = -375 + 1180 }}}
{{{ 805 = 805 }}}
OK