Explanation:

To find the area of the trapezium:

- Formula: Area = (1/2) × (sum of parallel sides) × (distance between them)

- Parallel sides are given as 10 cm and 20 cm.

- Distance (or height) between them is 5 cm.

- Plug into formula: Area = (1/2) × (10 + 20) × 5 = (1/2) × 30 × 5 = 75 cm².

Options:

1. 50 cm²: Incorrect, calculation error.

2. 60 cm²: Incorrect, calculation error.

3. 45 cm²: Incorrect, calculation error.

4. 75 cm²: Correct

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