B) { y = -2x, x - 2y = 0;

1. Substitute y = -2x into the second equation: x - 2(-2x) = 0.
2. Simplify: x + 4x = 0, so 5x = 0, which means x = 0.
3. Substitute x = 0 back into y = -2x to get y = 0.
4. Solution: (0, 0).