Find the relation if `z_1, z_2, z_3, z_4` are the affixes of the vertices of a parallelogram taken in order.

Explanation

To find the relation among the affixes \( z_1, z_2, z_3, z_4 \) of the vertices of a parallelogram taken in order, we can use the property that the diagonals of a parallelogram bisect each other.

### Step-by-Step Solution:

1. **Identify the vertices**: Let the vertices of the parallelogram be represented by the complex numbers \( z_1, z_2, z_3, z_4 \). We can assume that these points are in the order \( A, B, C, D \) respectively.

2. **Use the property of diagonals**: In a parallelogram, the diagonals bisect each other. This means that the midpoint of diagonal \( AC \) is the same as the midpoint of diagonal \( BD \).

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