Solve: y=2x,x+y=9y = 2x, x + y = 9y=2x,x+y=9.
(3,6)(3, 6)(3,6)
(6,3)(6, 3)(6,3)
(4.5,4.5)(4.5, 4.5)(4.5,4.5)
(1,2)(1, 2)(1,2)