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Answer:
A. 500 cm²
Explanation:
The height of the piece of cardboard is the same as the height of the prism: 20 cm.
The width of the piece of cardboard is the sum of the side lengths of the prism: 7 cm + 9 cm + 9 cm = 25 cm.
The area of the cardboard is the product of its height and width.
A = HW
A = (20 cm)(25 cm) = 500 cm²