The solution to the system of equations should be true for both equations. This means that if you substitute -2 into both equations, you should get 6 as the y value for both equations.
They gave you a graph, and to find the solution from the graph, you just look at which point is shared by both lines, or at which point both lines intersect.
There is also a mathematical way to do it using substitution and elimination, but you should master the graphing method first before moving onto those.
