3 hm² + 2 dam²+100m² = …. are

3 hm² + 2 dam² + 100 m²
= (3 × 10.000) m² + (2 × 100) m² + 100 m²
= 30.000 m² + 200 m² + 100 m²
= 30.300 m²
= 30.300 are