Solve by substitution


Just plug in y=-x-1 into y+x=3
So we get:

Simplify that:

And since that is not true, that means this system of equations has no solutions!
(0,0)
(0.1, 1.1)
(0.5, 5.5)
(0.8, 8.8)
(1,11)
(2,22)
(3,33)
(4,44)
(5,55)
(10,110)
(11, 121)
(20, 220)
(30, 330)
(90, 990)
etc, etc