Given the system x+y=2,2x+2y=4,3x+3y=6x+y=2, 2x+2y=4, 3x+3y=6x+y=2,2x+2y=4,3x+3y=6, what is the solution set?
A unique point
An empty set
A line in R2\mathbb{R}^2R2
A plane in R3\mathbb{R}^3R3