Question 1064668
Start with a general equation,
{{{Ax+By=1}}}
Then use the points to solve for A and B.
{{{A(3)+B(0)=1}}}
{{{3A=1}}}
{{{A=1/3}}}
and
{{{A(0)+B(-9)=1}}}
{{{-9B=1}}}
{{{B=-1/9}}}
So,
{{{x/3-y/9=1}}}
{{{highlight(3x-y=9)}}}