How do you graph the linear system and estimate the solution: #y=-x, y=2x+3#?
Set up a table of x and y value and calculate at least two sets of points for each line. Plot the lines and then extend them until they intersect. The intersection of the lines is the solution.
Depending on the resolution of your graph you may be able to read the value directly from your graph. It should be the point (-1, 1).