I need to show my work. I am solving for y.

X + 2Y = 2

To get Y alone:

X + 2Y = 2 -> you need to cancel X on the Y side, so you subtract X since it is positive on
both sides (if X was negative, you would add X to both sides)
X - X + 2y = 2 - X -> (X - X = 0) the X's cancel out
2Y = 2 - X -> To get Y alone, you have to divide 2 to both sides
(2Y)/2 = (2 - X)/2 -> since 2/2 = 1, the 2's cancel out, leaving Y alone
Y = (2 - X)/2

to prove it, let's say X = 1

1 + 2Y = 2
1 - 1 + 2Y = 2 - 1
0 + 2Y = 1
(2Y)/ 2 = 1/2
Y = 1/2

X=1, Y = 1/2
X + 2Y = 2
1 + 2 * (1/2) = 2
1 + 2/2 = 2
1 + 1 = 2
2 = 2