y>3 is represented graphically by the area above the line y=3.
Since y>3 for the equation y=-3x+2, -3x+2>3, 2-3>3x, -1>3x, so 3x<-1, x<-⅓.
The algebraic solution is x<-⅓, y<3, but y is dependent on x, and this relationship is represented by a line. But the line is semi-infinite in length. The point (-⅓,3) is not on the line, and this point is the lower limit of the length of the line. x∈(-∞,-⅓) and y∈(3,∞) where y=-3x+2. The graph below illustrates the solution. The shaded area represents y>3 and the red line y=-3x+2. The solution is represented by that portion of the red line to the left of the intersection with the dotted line y=3.
Picture by courtesy of Desmos.