-2x+3y=-15
              2(x-2y)=2(11)     <--------Multiply both sides by 2
                                    

             -2x+3y=-15
              2x-4y= 22     <--------Add the 2 equations
         -----------------
              0x -y=7
                                    

Check:

             -2(-3)+3(-7)=-15
               (-3)-2(-7)=11     Plug in (-3,-7)
                                    

                   6+-21=-15
               (-3)+14=11     Plug in (-3,-7)
                                    

                   -15=-15            Works
                    11=11             Works
                                    

Check:

works

works


3.
To solve the system graphically, we need to graph the inequalities. To do this we must make them an equation and solve for y
Solve for y
Make an equation
Subtract 3x from both sides
Divide both sides by 4. Now we can graph this equation
Solve for y
Make an equation
Subtract x from both sides
Divide both sides by 3. Now we can graph this equation
Since x and y is greater than x, we only need to graph these equations in the 1st quadrant (the upper left portion of the graph). So the graphs look like

To complete this we need to test which points will satisfy this set of inequalities. Let's try (0,0) plug this into

Which is true
Now try (0,0), plug this into

Which is true. This means you shade the region that contains (0,0) for both inequalities, which is below the graph for both. Since these regions overlap, you would ultimately shade their overlapping region, which is bounded by the x and y axises and the lines. If you want a picture email me and I'll send you one to give you an idea of what it looks like. Hope this helps.