1. The problem asks to find the expressions representing the two quantities David should use to approximate the amount of metal in a nut, which is a rectangular prism with a cylindrical hole. 2. To approximate the amount of metal, David needs to find the volume of the entire block and subtract the volume of the hole. 3. The volume of the rectangular prism (block) is given by the formula $$V_{block} = l \times w \times h$$ where $l$ is length, $w$ is width, and $h$ is height. 4. The volume of the cylindrical hole is given by the formula $$V_{cylinder} = \pi r^2 h$$ where $r$ is the radius of the hole and $h$ is the height (same as the block's height). 5. Therefore, the two expressions David should use are: - The volume of the block: $l \times w \times h$ (option D) - The volume of the cylindrical hole: $\pi r^2 h$ (option C) 6. The amount of metal is approximated by the difference: $$\text{Metal volume} = l \times w \times h - \pi r^2 h$$ 7. Hence, the correct answers are C and D.