To convert the measurements, we can use the following relationships:

1. **For meters and decimeters**:
- 1 meter (m) = 10 decimeters (dm)

2. **For square kilometers and hectares**:
- 1 square kilometer (km²) = 100 hectares (ha)

**Calculating 7m 5dm in meters:**
- Convert 5 dm to meters:
- \( 5 \, \text{dm} = \frac{5}{10} \, \text{m} = 0.5 \, \text{m} \)

- Now add it to 7 m:
- \( 7 \, \text{m} + 0.5 \, \text{m} = 7.5 \, \text{m} \)

So, **7m 5dm = 7.5m**.

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**Calculating 9 km² 75 ha in km²:**
- Convert 75 ha to km²:
- \( 75 \, \text{ha} = \frac{75}{100} \, \text{km}^2 = 0.75 \, \text{km}^2 \)

- Now add it to 9 km²:
- \( 9 \, \text{km}^2 + 0.75 \, \text{km}^2 = 9.75 \, \text{km}^2 \)

So, **9km² 75ha = 9.75km²**.

### Final Answers:
- 7m 5dm = **7.5m**
- 9km² 75ha = **9.75km²**