Question 1143048
You are given 2 actual points, which is enough
to give you the slope
( 2,30 )
( 9,16 )
The slope is [ change in y ] / [ change in x ]
{{{ m = ( 30 - 16 ) / ( 2 - 9 ) }}}
{{{ m = 14 / (-7)  }}}
{{{ m = -2 }}}
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Now you can use point ( x, 10 ) and either of the 
given points to find {{{ x }}}
{{{ ( 30 - 10 ) / ( 2 - x ) = -2 }}}
{{{ 20 / ( 2 - x ) = -2 }}}
{{{ 2 - x = 20/(-2) }}}
{{{ 2 - x = -10 }}}
{{{ x = 12 }}}
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Find the equation
{{{ y = m*x + b }}}
{{{ y = (-2)*x + b }}}
Use the point ( 12, 10 ) or one of the other 2 points
{{{ 10 = (-2)*12 + b }}}
{{{ 10 = -24 + b }}}
{{{ b = 34 }}}
The equation is:
{{{ y = -2x + 34 }}}
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check:
does it go through ( 9, 16 ) ?
{{{ 16 = -2*9 + 34 }}}
{{{ 16 = -18 + 34 }}}
{{{ 16 = 16 }}}
OK
You can check ( 2, 30 )