First Solution
-2x + y = 1
-2x + 2x + y = 1 + 2x
y = 1 + 2x
Second Solution
-2x + y = 1
-2x + y - y = 1 - y
-2x = 1 - y
-2 -2
x = -0.5 + 0.5y
0.5 + x - x = -0.5 + 0.5 - x + 0.5y
0.5 = -x + 0.5y
-0.5y - 0.5 = -x + 0.5y - 0.5y - 0.5
2 · (-0.5y) = 2(-x - 0.5)
y = -2x - 1
Third Solution
-2x + y = 1
-2x + y - 1 = 1 - 1
-2x + y - 1 = 0
-2x + 2x + y - 1 = 2x
y - 1 = 2x
y - 1 + 1 = 2x + 1
y = 2x + 1