Reason: We can only get one outcome, and that outcome could be a red, a blue, or a green marble. We only list one unique item at a time. The order doesn't matter. The sample space represents all possible outcomes.
First, graph both equations on a rectangular coordinate system (see attached screenshot). Then, simply figure out where these two lines intersect. Since they intersect at (2,3), x=2 and y=3.
Plugging these values in the equations for x and y, you can see if these are the correct answers:
(3)=3(2)-3, (2)+(3)=5
Since both of these are true, you have the right answer.