Question

x+y=2. solve for x and y

Answer 1

x+y=2
subtract either x or y on both side depending on what you want and in this case you need both! so...
y=2-x
and x=2-y

Answer 2

questions? :o

Answer 3

since you have one equation and two unknowns, then there is no 1 solution for the equation. all you can do is specify x in terms of y or y in terms of x e.g.
x = 2-y or y = 2-x