1. **State the problem:** We need to find the area of a trapezium with parallel sides of lengths 9 cm and 30 cm, and a height of 8 cm. 2. **Formula for the area of a trapezium:** $$\text{Area} = \frac{1}{2} \times (\text{sum of parallel sides}) \times \text{height}$$ 3. **Identify the values:** - Top base $a = 9$ cm - Bottom base $b = 30$ cm - Height $h = 8$ cm 4. **Substitute the values into the formula:** $$\text{Area} = \frac{1}{2} \times (9 + 30) \times 8$$ 5. **Simplify inside the parentheses:** $$9 + 30 = 39$$ 6. **Calculate the area:** $$\text{Area} = \frac{1}{2} \times 39 \times 8$$ 7. **Multiply:** $$\frac{1}{2} \times 39 = \frac{39}{2}$$ 8. **Final multiplication:** $$\frac{39}{2} \times 8 = 39 \times \cancel{\frac{8}{2}} = 39 \times 4 = 156$$ 9. **Answer:** The area of the trapezium is $156$ square centimeters.