Question 1154765
One of the lines:
(1,2) and (0,5);
{{{y=((5-2)/(0-1))x+5}}}
{{{y=-3x+5}}}



The OTHER line:
{{{y=(1/3)x+b}}}
{{{b=y-x/3}}}
since also pass through (1,2), then
{{{b=2-1/3}}}
{{{b=6/3-1/3=4/3=1&1/3}}}
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This other line is  {{{highlight(y=x/3+1&1/3)}}}.