I'm pretty sure it would be <span>x - y + 1 = 0 because if you plug in one of the coordinates into each equation, this is the only one that works.
</span><span>y - x + 1 = 0
2 - 1 + 1 = 0
2 = 0 not correct
</span><span>x - y + 1 = 0
1 - 2 + 1 = 0
0 = 0 correct
</span><span>-x - y + 1 = 0
-1 - 2 + 1 = 0
-2 = 0 not correct
</span>
You can have 30 and a negative 6. IDK. Hope it can help a bit.
It is a 50 percent chance. This is because there is only two possibilities that can occur. It does not matter how many times the coin has been flipped.