Question 418286
the points are:
(x1,y1) , (x2,y2)
The formula is:
{{{ (y - y1) / (x - x1) = (y2 - y1) / (x2 - x1) }}}
given:
(4,1) (6,3) 
{{{ (y - 1) / (x - 4) = (3 - 1) / (6 - 4) }}}
{{{ (y - 1) / (x - 4) = 1 }}}
{{{ y - 1 = x - 4}}}
{{{y = x - 3}}}
check answer:
(6,3)
{{{y = x - 3}}}
{{{3 = 6 - 3}}}
{{{3 = 3}}}
OK
(4,1)
{{{y = x - 3}}}
{{{1 = 4 - 3}}}
{{{1 = 1}}}
OK