Question 892341
Slope is ( change in y ) / ( change in x )
m: ( 2,5 ) , ( 5,2 )
Slope of line m:
{{{ ( 2 - 5 ) / ( 5 - 2 ) = -3/3 }}}
{{{ -3/3 = -1 }}}
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n: ( 5, -8 ) , ( 11, z )
Line n is a parallel line so, 
{{{ ( z -(-8) )  / ( 11 - 5 ) = -1 }}}
{{{ ( z + 8 ) / 6 = -1 }}}
{{{ z + 8 = -6 }}}
{{{ z = -14 }}}
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check:
{{{ ( z -(-8) )  / ( 11 - 5 ) = -1 }}}
{{{ ( -14 -(-8) )  / ( 11 - 5 ) = -1 }}} 
{{{ ( -14 + 8 ) / 6 = -1 }}}
{{{ -6/6 = -1 }}}
{{{ -1 = -1 }}}
OK