y <= 0.5
y + 2.5 <= 0.5 + 2.5 y + 2.5 <= 3
y - 3.5 <= 0.5 - 3.5 y - 3.5 <= -3
10y <= 0.5 * 10 10y <= 5
y <= 0.5 -y >= -0.5
- y >= -0.5 4-y >= 4 - 0.5 4-y >= 3.5
4y <= 2 -4y >= -2
4y - 3 <= 4*0.5 - 3 4y - 3 <= -1
-2y >= -1 -2y + 3 >= 2
