Question 661988
{{{ ( y - 2 ) / ( x - 1 ) = ( 16 - 2 ) / ( 3 - 1 ) }}}
{{{ ( y - 2 ) / ( x - 1 ) = 14 / 2 }}}
{{{ ( y - 2 ) / ( x - 1 ) = 7 }}} 
{{{ y - 2 = 7*( x - 1 ) }}}
{{{ y - 2 = 7x - 7 }}}
{{{ 7x - y = 5 }}}
check:
does it go through (3,16) ?
{{{ 7*3 - 16 = 5 }}}
{{{ 21 - 16 = 5 }}}
{{{ 5 = 5 }}}
does it go through (1,2) ?
{{{ 7*1 - 2 = 5 }}}
{{{ 7 - 2 = 5 }}}
{{{ 5 = 5 }}}
OK