Calculate number of sigma `(sigma)` and pi` (pi)` bonds in the above structures (i-iv).

Explanation

To calculate the number of sigma (σ) and pi (π) bonds in the given structures (i-iv), we will analyze each structure step by step.

### Structure i:
1. **Identify the Bonds**:
- The structure consists of two methyl groups attached to a carbon, which also has one hydrogen.
- There are double bonds present in the structure.

2. **Count the Pi Bonds**:
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