Question 70078
Each ordered pair is simply (x,y). For instance, (0,4) can written as x=0 and y=4.
So to see if the solutions work, plug them into the equation
{{{3x-y=12}}}
<p>
{{{3(0)-4=12}}}check to see if 1st pair works
{{{-4=12}}} false
<p>
{{{3(4)-0=12}}}check to see if 2nd pair works
{{{12=12}}} true
<p>
{{{3(-1)-15=12}}}check to see if 1st pair works
{{{-3-15=12}}}
{{{-18=12}}} false (edit: sorry I read the problem wrong)
So only (4,0)  is the only solutions.